Searched: parent.name = 'ResearchTopics'

Analysis of Variance Lead Author(s): Main.NancyHills The term analysis of variance (ANOVA) describes a group of inferential statistical tests that were developed...

r17 - 28 Dec 2010 - 01:33 by MaryBanach

Ascertainment Bias In scientific research, ascertainment bias occurs when false results are produced by non random sampling and conclusions made about an entire ...

r11 - 03 Apr 2012 - 19:13 by MaryBanach

Assumptions: Cumulative Incidence and Incidence Rate Lead Author(s): Jeff Martin, MD Assumption No Temporal/Secural Trends Calculating cumulative incidence with...

r2 - 04 Jun 2009 - 20:45 by MaryB

Baseline Data Lead Author(s): Information gathered at the beginning of a study from which variations found in the study are measured. A person's health status bef...

r9 - 03 Apr 2012 - 19:16 by MaryBanach

Bernoulli distribution In probability theory and statistics, the Bernoulli distribution, named after Swiss scientist Jakob Bernoulli, is a discrete probability di...

r2 - 14 Apr 2009 - 22:30 by CTSpediaAdmin

Confounding Bias Lead Author(s): Jeff Martin, MD Properties of a True Confounder Is the exposure (or predictor variable), marked E, associated with disease (or...

r32 - 15 Dec 2010 - 01:33 by MaryBanach

Reducing Confounding During Data Analysis Lead Author(s): Jeff Martin, MD Methods for Reducing Confounding During Data Analysis: Stratification In the data a...

r19 - 04 Jun 2009 - 23:30 by MaryB

Properties of a Confounder Association with Disease Lead Author(s): Jeff Martin, MD Refined Properties of a True Confounder Association with Disease When w...

r10 - 05 Jun 2009 - 22:12 by MaryB

Properties of a Confounder Association with Exposure Lead Author(s): Jeff Martin, MD Refined Properties of a True Confounder Association with Exposure Wh...

r9 - 05 Jun 2009 - 22:21 by MaryB

Confounder or Intermediate Variable? Lead Author(s): Jeff Martin, MD What Is Not A Confounder? A variable that is an intermediate step in the causal path under s...

r7 - 11 Jun 2009 - 20:16 by MaryB

Types of Confounding Bias Lead Author(s): Jeff Martin, MD Magnitude and Direction of Confounding After adjusting for confounding variables, we will have a measur...

r4 - 01 Jun 2009 - 17:33 by MaryB

Bias or Systematic Error (Validity) Lead Author(s): Jeff Martin, MD Origin of the Term Bias Bias refers to a systematic error. The origin of the word appears to...

r17 - 15 Dec 2010 - 01:49 by MaryBanach

Measurement Bias Lead Author(s): Jeff Martin, MD Technical Definition: It is the bias, or deviation from the truth, that it is caused when any measurement collec...

r26 - 03 Feb 2012 - 23:10 by PeterBacchetti

Selection Bias Technical definition: Bias that is caused when individuals have different probabilities of being included in the study according to relevant study...

r23 - 19 May 2009 - 20:06 by MaryB

Selection Bias Analytic Study Lead Author(s): Jeff Martin, MD Unbiased Sampling in Analytic Studies In an analytic study or case control study, we are looking ...

r4 - 05 Jun 2009 - 20:26 by MaryB

Selection Bias Cohort Study or Randomized Clinical Trial Selection Bias in Cohort Studies Less Likely Among initially selected subjects, selection bias in a co...

r3 - 03 Apr 2012 - 23:10 by MaryBanach

Selection Bias Cross Sectional Study Lead Author(s): Jeff Martin, MD Cross sectional Study Design As seen in the diagram below, there is an underlying cohor...

r3 - 05 Jun 2009 - 23:36 by MaryB

Selection Bias Descriptive Study Lead Author(s): Jeff Martin, MD Unbiased Sampling in Descriptive Studies Here is a schematic representation of what we hope ...

r5 - 15 Dec 2010 - 21:51 by MaryBanach

Biological Marker See Also * Biomarker

r2 - 14 Apr 2009 - 22:30 by CTSpediaAdmin

Case Control Odds Ratio Lead Author(s): Jeff Martin, MD Case Control Odds Ratio Odds ratio (OR) of exposure in cases and controls is the measure of association ...

r2 - 03 Feb 2012 - 23:10 by PeterBacchetti

Case Control Study Lead Author(s): Jeff Martin, MD Case Control Design The main advantage of case control designs is that it allows you to sample the experienc...

r41 - 03 Apr 2012 - 18:31 by MaryBanach

Box Plot Lead Author(s): Erin Dienes Definition of Box Plot A box plot, also known as a box and whiskers plot, is a graphical method that is based on the quar...

r4 - 07 Sep 2011 - 22:03 by MaryBanach

Causal Diagrams or Directed Acyclic Graphs (DAGs) Lead Author(s): Jeff Martin, MD Definition of Causal Diagrams The stick and box figure below is known as a c...

r4 - 05 Jun 2009 - 20:29 by MaryB

Censoring Lead Author(s): Jeff Martin, MD Three Ways Censoring Occurs 1) Death (if death is not the study outcome) 2) Loss to follow up (refuse, move, or canno...

r14 - 05 Jun 2009 - 20:45 by MaryB

Chi Square versus Fisher's Exact FORUM QUESTION: Julia St George 22 May 2009 12:00 Can you explain the difference between Fisher's exact test and the chi sq...

r2 - 05 Aug 2011 - 15:25 by MaryBanach

Clinical Bias The study of medical conditions begins with anecdotal reports. By their nature, such reports only include those referred for diagnosis and treatment...

r2 - 14 Apr 2009 - 22:30 by CTSpediaAdmin

Clinical Epidemiology Epidemiology is the study of factors affecting the health and illness of populations, and serves as the foundation and logic of intervention...

r2 - 14 Apr 2009 - 22:34 by CTSpediaAdmin

Cohort Study Lead Author(s): Mark Pletcher, MD; Jeff Martin, MD Definition of a Cohort Study In a cohort study, the study base is an explicitly defined group of...

r39 - 03 Apr 2012 - 23:12 by MaryBanach

Common Rule Lead Author(s): Jeff Martin, MD Minimal risk means that the probability and magnitude of harm or discomfort anticipated in the research are not greate...

r4 - 04 Jun 2009 - 23:59 by MaryB

Community Engagement Links * CTSI Community Engagement FAQ

r2 - 14 Apr 2009 - 22:30 by CTSpediaAdmin

Confidence Interval Lead Author(s):

NEW - 03 Jun 2009 - 18:23 by MaryB

Confidence intervals (CIs) Lead Author(s): Main.PeterBacchetti These are used to indicate the uncertainty around an estimated or observed association, difference,...

r13 - 01 Feb 2012 - 19:54 by PeterBacchetti

Return to CTSpedia Web Home Conflicts of interest Physicians should not allow a conflict of interest to influence medical judgment. In some cases, conflicts are...

r4 - 03 Apr 2012 - 20:07 by MaryBanach

Confounding Factor

r2 - 14 Apr 2009 - 22:30 by CTSpediaAdmin

Continuous Data / Variable Lead Author(s): Definition of Continuous Data / Variable

NEW - 05 Jun 2009 - 22:30 by MaryB

Continuous Random Variable A continuous random variable is one that can assume values corresponding to any of the points contained in an interval. Some examples i...

NEW - 13 Apr 2010 - 04:03 by ErinEsp

Cost Benefit Analysis Lead Author(s): Definition of Cost Benefit Analysis

NEW - 05 Jun 2009 - 23:21 by MaryB

Cost Effectiveness Analysis A cost effectiveness analysis compares decisions based on units of money per health outcome. For example, dollars per life saved, dol...

r8 - 14 Apr 2009 - 22:30 by CTSpediaAdmin

Covariate Lead Author(s): Definition of Covariates

NEW - 05 Jun 2009 - 23:23 by MaryB

Cox and Proportional Hazard FORUM QUESTION: Main.BarbaraGrimes 24 Aug 2009 13:09 If the proportional hazards assumption is not met for a predictor in a Cox m...

r2 - 05 Aug 2011 - 17:04 by MaryBanach

Proportional Hazards Regression See discussion in Vanderbilt Biostatistics

NEW - 04 Aug 2011 - 15:41 by MaryBanach

Cross Sectional Study Lead Author(s): Jeff Martin, MD Definition of a Cross Sectional Study A cross sectional study can be described as a sample of a populatio...

r29 - 03 Feb 2012 - 23:10 by PeterBacchetti

Decision Analysis Lead Author(s): Clay Johnston, MD, PhD Decision analysis is an explicit, quantitative method for making (or at least thinking about) decisions i...

r9 - 05 Jun 2009 - 23:43 by MaryB

Decision Tree Lead Author(s): Definition of Decision Tree

NEW - 10 Jun 2009 - 19:44 by MaryB

Mean The mean, also called the average or the arithmetic mean , is often used as a summary of the center of a set of numbers, such as the ages of all the parti...

r4 - 29 Jun 2013 - 05:54 by PeterBacchetti

Median The median of a set of quantitative data (a set of numbers) is the middle number when the measurements are arranged in ascending or descending order. Supp...

NEW - 24 May 2010 - 17:09 by ErinEsp

Mode The mode is the measurement that occurs most frequently in the data set. The mode is a measure of central tendency as it shows where the data tend to concent...

NEW - 24 May 2010 - 17:11 by ErinEsp

Reliability Lead Author(s): Erin Esp Definition Reliability is the consistency of a set of measurements or of a measuring instrument. In short, reliability ...

r6 - 27 Sep 2012 - 15:48 by MaryBanach

Robust Statistics A robust statistic is a statistic that is resistant to errors in the results caused by outliers or other small departures from model assumption...

r2 - 24 May 2010 - 17:13 by ErinEsp

Degrees of Freedom Lead Author(s): Main.ErikGregory Definition of Degrees of Freedom To perform t tests we often need to determine the number of degrees of free...

r5 - 04 Oct 2010 - 01:42 by MaryBanach

Outcome or Dependent Variable In regression models, these terms refer to the variable that is to be predicted or explained in terms of the predictor or independen...

r3 - 14 Apr 2009 - 22:30 by CTSpediaAdmin

Descriptive Variable Lead Author(s): Definition of a Descriptive Variable

NEW - 10 Jun 2009 - 20:01 by MaryB

Difference versus Ratio Lead Author(s): Jeff Martin, MD Ratio versus Difference in Cohort Study There are two basic ways to compare measures of association in ...

r4 - 10 Jun 2009 - 20:15 by MaryB

Ecological Study Lead Author(s): Definition of an Ecological Study

r5 - 05 Jun 2009 - 23:51 by MaryB

Example: Age Adjust Petrochemical Workers Lead Author(s): Jeff Martin, MD Person Time Rates for Cohort Analysis In Austin's (1983) study of petrochemical worke...

r3 - 11 Jun 2009 - 19:48 by MaryB

Example: Backwards Strategy MRSA Lead Author(s): Jeff Martin, MD Kleinbaum provides an example of using backwards strategy to adjust for potential confounders. ...

r4 - 03 Feb 2012 - 23:10 by PeterBacchetti

Example: Selection Bias Nuclear Bomb Testing Lead Author(s): Jeff Martin, MD Example of Selection Bias: Leukemia and Nuclear Bomb Testing History Smoky Atom...

r2 - 11 Jun 2009 - 20:42 by MaryB

Example: Selection Bias Breast Cancer Lead Author(s): Jeff Martin, MD Breast Cancer Study This is an example of selection bias in a cross sectional study. Kel...

r2 - 11 Jun 2009 - 20:35 by MaryB

Example: Selection Bias Pancreatic Cancer Lead Author(s): Jeff Martin, MD Bias in Analytic Study: Coffee and Pancreatic Cancer Study 1: Biased Overestimate ...

r4 - 03 Feb 2012 - 23:10 by PeterBacchetti

Example: Bias Study of Spermicide Use and Down Syndrome Lead Author(s): Jeff Martin, MD Analysis of Spermicide Use and Down Syndrome Data We are looking at ...

r3 - 11 Jun 2009 - 19:52 by MaryB

Example: Selection Bias in Politics Lead Author(s): Jeff Martin, MD Examples of Selection Bias in Political Studies 1948 Presidential Election The 1948 preele...

r2 - 11 Jun 2009 - 20:37 by MaryB

Case Control Study Example Netherlands Cohort on Vitamin Intake Lead Author(s): Jeff Martin, MD Abstract from Zeegers (Zeegers' abstract) below is an example ...

r3 - 11 Jun 2009 - 19:55 by MaryB

Example of Case Control Study Design Kaiser Sigmoidoscopy Study Lead Editor(s): Jeff Martin, MD Case Control Study Design Choices Kaiser Research Division 199...

NEW - 28 May 2009 - 20:07 by MaryB

Case Control Study Example Rare Disease Lead Author(s): Jeff Martin, MD Rare Disease Assumption The rare disease assumption says that if the incidence of ...

r4 - 11 Jun 2009 - 19:57 by MaryB

Example: Cohort Study Framingham Lead Author(s): Jeff Martin, MD Framingham Study Impact of Diabetes The Framingham Study reports on the impact of diabetes...

r2 - 11 Jun 2009 - 19:59 by MaryB

Example: Counfounding Bias HIV and Needlestick Lead Editor(s): Jeff Martin, MD Treatment after HIV Needlestick Exposure An example of counding can be found i...

r5 - 03 Feb 2012 - 23:10 by PeterBacchetti

Example: Confounding Bias Night Lite Lead Author(s): Jeff Martin, MD Example of Confounding: Night Lite Confounding can be found in Quinn's study of myopia and...

r2 - 05 Jun 2009 - 22:27 by MaryB

Example: Cumulative Incidence Denominator GI Illness Lead Author(s): Jeff Martin, MD GI Outbreak MMWR reported "Pleisomonas shigelloides and Salmonella sero...

r3 - 10 Jun 2009 - 19:52 by MaryB

Example: Cumulative Incidence SEER Program Lead Author(s): Jeff Martin, MD Long Term Survival NCI SEER Program In the following example from Brenner, th...

r2 - 04 Jun 2009 - 23:52 by MaryB

Example of Differential Misclassification Bias Nurses Health Study Melanoma Risk Lead Author(s): Jeff Martin, MD Differential Misclassification of Exposure...

r6 - 03 Feb 2012 - 23:10 by PeterBacchetti

Example of Differential Misclassification Bias Pregnancy and Congenital Malformations Lead Author(s): Jeff Martin, MD Differential Misclassification of Exposur...

r3 - 10 Aug 2011 - 19:42 by MaryBanach

Example: Cumulative Incidence Survival Lead Author(s): Jeff Martin, MD Cumulative Incidence McDonald reports cumulative incidence at four 5 year time interval...

r4 - 11 Jun 2009 - 20:03 by MaryB

Example: Incidence Reporting What Is Missing? Lead Author(s): Jeff Martin, MD Measures Loosely Called Incidence Number of Events (E) Count of the number of ...

r2 - 11 Jun 2009 - 20:11 by MaryB

Examples of Incident Density Sampling Dynamic Primary Study Base Lead Author(s): Jeff Martin, MD Example 1: Alcohol Consumption and Breast Cancer The abstract...

r3 - 10 Jun 2009 - 20:32 by MaryB

Example: Qualitative Interaction Pregnancy and Coffee Study Lead Author(s): Jeff Martin, MD Study of Effects of Caffeine Consumption on Delayed Conception S...

r5 - 11 Jun 2009 - 20:30 by MaryB

Example: Intermediate Variable CAD Lead Author(s): Jeff Martin, MD Is HDL a Confounder or an Intermediary? We are looking at the relationship between exer...

r3 - 11 Jun 2009 - 20:16 by MaryB

Example: Intermediate Variable HIV CCR5 Lead Author(s): Jeff Martin, MD CCR5 Receptor on the CD4 Cells Taylor published findings on the human cellular recept...

r2 - 11 Jun 2009 - 20:18 by MaryB

Example: Selection Bias Loss to Follow Up AIDS Lead Author(s): Jeff Martin, MD Losses to follow up are a grave problem in AIDS studies. Progression to AIDS ...

r3 - 11 Jun 2009 - 20:36 by MaryB

Example: Lost to Follow up HCV and HIV Lead Author(s): Jeff Martin, MD Many times lost to follow up data is not presented. First Example from a Study with HI...

r3 - 11 Jun 2009 - 20:20 by MaryB

Graphical Examples of Misclassification Bias Lead Author(s): Jeff Martin, MD The effects of reduced sensitivity of the exposure measurement and/or reduced specifi...

r4 - 03 Feb 2012 - 23:10 by PeterBacchetti

Example of Misclassification Bias Non Differential Exposure Cohort Study Lead Author(s): Jeff Martin, MD Figure Misclassification of Exposure Variable Fle...

r4 - 05 Jun 2009 - 21:23 by MaryB

Example of Misclassification Bias Non Differential Exposure Imperfect Sensitivity Lead Author(s): Jeff Martin, MD Measurement bias is affected by imperfect s...

r6 - 03 Feb 2012 - 23:10 by PeterBacchetti

Example of Misclassification Bias Non Differential Exposure Imperfect Specificity Lead Author(s): Jeff Martin, MD Measurement bias results from imperfect spec...

r6 - 03 Feb 2012 - 23:10 by PeterBacchetti

Example of Misclassification Bias Non Differential Misclassification of Outcome Lead Author(s): Jeff Martin, MD Misclassification of the outcome results in meas...

r2 - 11 Jun 2009 - 20:26 by MaryB

Example of Misclassification Bias Outcome Variable Cohort Study Lead Author(s): Jeff Martin, MD Misclassification bias of the outcome variable does not reduc...

r3 - 21 Jun 2012 - 18:31 by MaryBanach

Example of Misclassification Bias Pertussis Vaccine 100% Specificity Lead Author(s): Jeff Martin, MD Misclassfication Bias In a cohort study we have a s...

r2 - 01 Jun 2009 - 17:04 by MaryB

Example of Misclassification Bias Imperfect Sensitivity and Specificity Lead Author(s): Jeff Martin, MD Measurement bias is affected by imperfect sensitivity a...

r5 - 03 Feb 2012 - 23:10 by PeterBacchetti

Example: Do Not Adjust Lung Cancer and Matches Lead Author(s): Jeff Martin, MD Crude and Adjusted Data Here is an example of what can happen when you adjust ...

r3 - 11 Jun 2009 - 20:29 by MaryB

Example: Person Time Incidence Pediatric Cardiomyopathy Lead Author(s): Jeff Martin, MD Study of Pediatric Cardiomyopathy Lipshultz 2003 Study presents: ...

r2 - 11 Jun 2009 - 20:07 by MaryB

Examples of Reporting or Ignoring Interactions Lead Author(s): Jeff Martin, MD These are guidelines for reporting or ignoring interactions. First consideration mu...

r3 - 11 Jun 2009 - 20:31 by MaryB

Example: Stratification Matches, Smoking, and Lung Cancer Lead Author(s): Jeff Martin, MD Reason for Stratification In the example below we are concerned abou...

r2 - 01 Jun 2009 - 18:04 by MaryB

Example: Incidence Time Varying Exposure Lead Author(s): Jeff Martin, MD Analysis of Changing Exposure and Disease Incidence Ray (2002) analyzed Medicaid rec...

r4 - 11 Jun 2009 - 20:09 by MaryB

Epidemiology Lead Author(s): Jeff Martin, MD Definition of Epidemiology The study of the distribution and determinants (causes) of disease e.g., cardiovascul...

r4 - 15 Dec 2010 - 00:41 by MaryBanach

Error in Clinical Research Lead Author(s): Jeff Martin, MD Missing the Truth What are the ways of missing the truth (ie getting the wrong answer)? There are two ...

r8 - 05 Jun 2009 - 20:56 by MaryB

Error, Type I See Educational Materials for a discussion of Type I Error

r3 - 03 Aug 2011 - 19:51 by MaryBanach

Error, Type II See Educational Materials for a discussion of Type II Error

r3 - 03 Aug 2011 - 19:49 by MaryBanach

Fisher's Exact Test Fisher's exact test is a statistical significance test used in the analysis of tables where sample sizes are small. It is named after its in...

r5 - 03 Apr 2012 - 19:18 by MaryBanach

Follow up Time Lead Author(s): Laurel Beckett, PhD; Jeff Martin, MD Definition of Follow up Time Example of Follow up Time Among 250 total subjects, 100 died d...

r20 - 03 Apr 2012 - 22:47 by MaryBanach

Framingham Heart Study The Framingham Heart Study is a cardiovascular study based in Framingham, Massachusetts. The study began in 1948 with 5,209 adult subjects ...

r6 - 03 Apr 2012 - 19:20 by MaryBanach

Geocoding There are multiple options and many resources on the Internet for learning how to geocode; in this case, for assigning an exact location to study partic...

NEW - 04 Aug 2011 - 19:10 by MaryBanach

Geometric Mean The geometric mean is often used to describe the center of a set of numbers that are right skewed, such as the C reactive protein values of partici...

NEW - 29 Jun 2013 - 05:50 by PeterBacchetti

Gold Standard Lead Editor(s): Jeff Martin, MD Gold Standard Individual measurements are the gold standard. Gold Standard in Confounding When considering all...

r5 - 03 Aug 2011 - 20:07 by MaryBanach

Group Randomized Study A group randomized study is a randomized trial in which the intervention is assigned to a group of people but the outcome is asses...

r5 - 15 Dec 2010 - 01:38 by MaryBanach

r2 - 14 Apr 2009 - 22:30 by CTSpediaAdmin

Halo effect The halo effect refers to a cognitive bias whereby the perception of a particular trait is influenced by the perception of the former traits in a sequ...

r6 - 03 Apr 2012 - 19:20 by MaryBanach

Hosmer Lemeshow Test (H L Test) Lead Author(s): Peter Bacchetti, PhD This provides a p value for the composite null hypothesis that a logistic regression model ha...

r5 - 12 Jun 2009 - 17:05 by MaryB

Use of Incidence Rate Compare Disease Incidence in a Cohort with Population Lead Author(s): Jeff Martin, MD Advantage of Using Incidence Rate There are a nu...

r6 - 03 Jun 2009 - 22:33 by MaryB

Compare Incidence from Time Varying Exposure Advantage of Using Incident Rates There are a number of advantages to using incident rates. One of them is to look ...

r9 - 05 May 2009 - 23:20 by MaryB

Use of Incidence Rate Calculate from Population Based Registries Advantage of Using Incidence Rate There are a number of advantages of rates. One is the abil...

r7 - 14 May 2009 - 23:21 by MaryB

Inference Lead Author(s): Jeff Martin, MD The goal of any study is make an accurate (true) inference or to find the truth about the source. There are two types o...

r5 - 15 Dec 2010 - 01:15 by MaryBanach

Integrated Data Repository An integrated data repository (IDR) containing aggregations of clinical, biomedical, economic, administrative, and public health data...

r3 - 11 May 2009 - 18:38 by CTSpediaAdmin

Intention to Treat Analysis See Educational Materials for Intent to Treat Analysis

r2 - 03 Aug 2011 - 20:35 by MaryBanach

Interactions versus Confounding Lead Author(s): Jeff Martin, MD Confounding vs Interaction How do confounding and interaction differ? Confounding: An extraneous ...

r18 - 02 Jun 2009 - 20:56 by MaryB

Multiplicative Interaction Lead Author(s): Jeff Martin, MD Definition of Multiplicative Interaction When there is interaction in terms of the ratio measure of ...

r15 - 05 Jun 2009 - 21:21 by MaryB

Additive Interaction Lead Author(s): Jeff Martin, MD Definition of Additive Interaction When there is interaction in terms of the difference measure of assoc...

r15 - 08 Apr 2010 - 21:01 by LinkT

Graphical Approach to Interaction Lead Author(s): Jeff Martin, MD Many texts use a graphical approach to depict interaction. To determine interactions we graphica...

r6 - 11 Jun 2009 - 22:04 by MaryB

Intra Class Correlation (ICC) In planning group randomized studies, we typically assume that the measurements between any pair of people in the same group have th...

r3 - 15 Dec 2010 - 01:38 by MaryBanach

Jackknife Jackknifing, which is similar to bootstrapping, is used in statistical inferencing to estimate the bias and standard error in a statistic, when a random...

r8 - 03 Apr 2012 - 19:50 by MaryBanach

Kaplan Meier Method for Calculating Cumulative Incidence Calculating Cumulative Incidence with the Kaplan Meier Method To calculate cumulative incidence we must ...

r3 - 21 Jun 2012 - 21:58 by MaryBanach

Explaining Low Kappa Value FORUM QUESTION: Main.BarbaraGrimes 05 Feb 2010 15:44 I have a set of data where 3 reviewers classified 20 subjects. The client is ...

r2 - 05 Aug 2011 - 17:05 by MaryBanach

Least Squares See Educational Materials for information on Least Squares

r4 - 03 Aug 2011 - 20:48 by MaryBanach

Length Bias Lead Author(s): Erik Gregory Definition of Length Bias Length bias refers to our tendency to select relatively long intervals of time when doing cr...

r6 - 23 Jul 2010 - 17:24 by MaryBanach

Likelihood The likelihood is defined as the probability of observing a given set of data, assuming a particular model of the process that generated them. It is o...

NEW - 28 Jan 2013 - 21:35 by PeterBacchetti

Likelihood Ratio Test This calculates a P value for a term in a regression model based on how much the likelihood worsens when the term is removed from the model...

NEW - 28 Jan 2013 - 21:48 by PeterBacchetti

Linear Regression Lead Author(s): Erin Dienes Definition of Linear Regression Regression analysis is a statistical methodology that utilizes the relationship b...

r11 - 01 May 2010 - 06:08 by ErinEsp

Linear Splines Lead Author(s): Peter Bacchetti, PhD A linear spline is used in regression models to allow a predictor to have a non linear effect on the outcome. ...

NEW - 25 Jun 2012 - 05:42 by PeterBacchetti

2 log likelihood ( 2 log L) Lead Author(s): Peter Bacchetti, PhD This is a measure of how well the fitted model matches the observed values of the outcome or depe...

r5 - 03 Jun 2009 - 18:28 by MaryB

Main.PeterBacchetti 22 Oct 2009 Outcome for Logistic Regression Lead Author(s): Peter Bacchetti, PhD For logistic regression, the outcome variable is generally a...

r2 - 01 Feb 2012 - 22:23 by PeterBacchetti

Logistic Regression Lead Author(s): Jeff Martin, MD Definition of Logistic Regression Logistic regression is the method of multivariable analysis used most often...

r9 - 22 Oct 2009 - 22:57 by PeterBacchetti

Lost to Follow up Lead Author(s): Jeff Martin, MD Main Threat to Validity in a Cohort Study "What is the effect of subjects who are lost to follow up on the in...

r8 - 15 Dec 2010 - 01:49 by MaryBanach

Mann Whitney Test See Educational Materials Stata and Statistical Tools R Function

NEW - 03 Aug 2011 - 22:36 by MaryBanach

Markov Processes See Educational Materials Markov Transitions

NEW - 03 Aug 2011 - 22:40 by MaryBanach

Maximum Likelihood Estimation This is a general strategy for estimating the parameters of a statistical model of the process that generated a set of data. The par...

NEW - 28 Jan 2013 - 21:38 by PeterBacchetti

Maximum Likelihood Estimate See SAS macro code and Educational Materials Stata

NEW - 03 Aug 2011 - 22:45 by MaryBanach

Measurement Scale See Educational Materials Stata

NEW - 03 Aug 2011 - 22:47 by MaryBanach

Measure of Central Tendency The central tendency of a set of measurements is the tendency of the data to cluster/center around certain numerical values. Some exa...

NEW - 24 May 2010 - 17:12 by ErinEsp

Medpedia http://www.medpedia.com The Medpedia Project is a long term, worldwide project to evolve a new model for sharing and advancing knowledge about health, me...

r4 - 15 Dec 2010 - 01:20 by MaryBanach

Median Reporting FORUM QUESTION: Main.BarbaraGrimes 06 Jul 2009 09:53 When the median of a measurement is reported in a manuscript, should the min,max or the...

r2 - 05 Aug 2011 - 17:03 by MaryBanach

Meta Analysis Lead Author(s): Clay Johnston, MD, PhD The clinical literature is overwhelming. On any topic important to clinical decision making, there are numer...

r8 - 15 Dec 2010 - 01:23 by MaryBanach

Minimal Risk According to the Common Rule, Minimal risk means that the probability and magnitude of harm or discomfort anticipated in the research are not...

r2 - 14 Apr 2009 - 22:30 by CTSpediaAdmin

Missing Data FORUM QUESTION: Julia St George 22 May 2009 11:44 I have done a survey of interns in which each person was asked 12 questions, before and after ...

r2 - 05 Aug 2011 - 15:21 by MaryBanach

Monte Carlo Simulation See directions for Monte Carlo simulation in Stata

NEW - 03 Aug 2011 - 22:55 by MaryBanach

Multicollinearity See Educational Materials: Multicollinearity Stata

NEW - 03 Aug 2011 - 22:59 by MaryBanach

Multiple Comparison Techniques See MCW Video on Multiple Comparison Techniques

NEW - 03 Aug 2011 - 23:04 by MaryBanach

Multiplicative Model See Educational Materials Stata and Multiplicative Model

NEW - 03 Aug 2011 - 23:12 by MaryBanach

Overview In 2006, the Clinical and Translational Science Institute (CTSI) was established at UCSF to aid researches in their work. From this, the Academic Researc...

r2 - 14 Apr 2009 - 22:30 by CTSpediaAdmin

Negative Confounding Lead Author(s): Jeff Martin, MD Definition of Negative Confounding When the measure of association has gotten larger after accounting for ...

r3 - 01 Jun 2009 - 18:11 by MaryB

Return to CTSpedia Web Home Nested Case Control Study This article is from Wikipedia; the original article is Nested case control study . The list of authors can...

r5 - 03 Apr 2012 - 19:52 by MaryBanach

Normal Distribution Lead Author(s): Erin Dienes The Normal distribution (also known as the Gaussian distribution or a bell curve ) is a type of pattern that a ...

r2 - 29 Jun 2013 - 05:35 by PeterBacchetti

Null Hypothesis Lead Author(s): Jeff Martin, MD The null hypothesis says that neither the exposure, the effects of treatment, or the resulting disease differed be...

r6 - 03 Feb 2012 - 23:10 by PeterBacchetti

Main.PeterBacchetti 21 Jun 2012 Numeric Variable This is a variable that is measured as a number on a quantitative scale, such as weight in kilograms or age in y...

NEW - 21 Jun 2012 - 05:25 by PeterBacchetti

Observational Study

r2 - 14 Apr 2009 - 22:30 by CTSpediaAdmin

Odds RatioThis is a measure of the association between a predictor (or independent) variable and a yes or no (binary) outcome (or dependent) variable. * A val...

r4 - 05 Feb 2015 - 20:19 by PeterBacchetti

Odds Ratio Expressions FORUM QUESTION: Julia St George 27 May 2009 11:09 I ran a logistic regression model and got an estimated odds ratio showing that whe...

r2 - 05 Aug 2011 - 17:01 by MaryBanach

Odds Ratio Lead Author(s): Jeff Martin, MD Odds Ratio = Four Probabilities Odds are already the ratio of two probabilities, so the odds ratio involves four pro...

r8 - 03 Feb 2012 - 23:10 by PeterBacchetti

Odds Ratio versus Risk Ratio Lead Author(s): Jeff Martin, MD Comparing OR and Risk Ratio OR Farther from 1 The schematic below illustrates the point that, unle...

r3 - 01 Jun 2009 - 17:12 by MaryB

Odds and Probability Lead Author(s): Jeff Martin, MD Odds = Probability of an Event Odds are most simply calculated as the number of events divided by the number...

r18 - 02 Jun 2009 - 17:25 by MaryB

Outcome or Dependent Variable Lead Author(s): Jeff Martin, MD Definition of Outcome or Dependent Variable These terms refer to the variable that is to be predict...

r10 - 22 Oct 2009 - 23:04 by PeterBacchetti

Overdispersion See Logistic Regression checklist for overdispersion and tools for checking dispersion.

NEW - 03 Aug 2011 - 23:43 by MaryBanach

Parametric Test Duke Online Course compares parametric versus non parametric tests

NEW - 04 Aug 2011 - 00:04 by MaryBanach

Partial Least Squares (PLS) Lead Author(s): Danh Nguyen, PhD Partial least squares can be viewed as a dimension reduction method that reduces the dimension of the...

r7 - 31 May 2011 - 22:14 by MaryBanach

Placebo, Placebo Effect Definition of a Placebo Definition of Placebo Effect Main.MaryB 27 Jan 2009

r2 - 14 Apr 2009 - 22:30 by CTSpediaAdmin

Polynomial Model Lead Author(s): Peter Bacchetti, PhD A polynomial model is used in regression models to allow a predictor to have a non linear effect on the outc...

r2 - 25 Jun 2012 - 05:42 by PeterBacchetti

Population Attributable Risk See discussion of population attributable risk in Study Design Educational Materials

NEW - 04 Aug 2011 - 15:28 by MaryBanach

Study Precision Good Precision Good Validity Consider that at the center of the target is the truth and that each shot at the target represents a study you con...

r4 - 16 Apr 2009 - 22:13 by MaryB

Predictive Value See discussion of predictive value in Evaluation of Diagnostic Tests Educational Material and in Principles of Hypothesis Testing

NEW - 04 Aug 2011 - 15:38 by MaryBanach

Predictor or Exposure Variable Lead Author(s): Jeff Martin, MD This variable is also referred to as the exposure, the explanatory variable, or the independent va...

r9 - 21 Jun 2012 - 05:31 by PeterBacchetti

Prevalence Ratio in Cross Sectional Study Lead Author(s): Jeff Martin, MD Definition of Prevalence Ratio The ratio of the proportion of the persons with disea...

r7 - 02 Jun 2009 - 17:40 by MaryB

Profile Likelihood Confidence Intervals The profile likelihood method determines lower and upper confidence bounds for a model parameter, such as a fitted regress...

NEW - 28 Jan 2013 - 21:43 by PeterBacchetti

Quadratic P value Lead Author(s): Peter Bacchetti, PhD This is a P value for the hypothesis that a numeric predictor has a linear effect. When P 0.05, this is us...

r5 - 25 Jun 2012 - 05:41 by PeterBacchetti

Random Error Chance (Reproducibility) Lead Author(s): Jeff Martin, MD Definition of Random Error In distinction to systematic error or bias, random error occu...

r10 - 05 Jun 2009 - 20:48 by MaryB

Randomized Trial A Type of Cohort Study Lead Editor(s): Jeff Martin, MD Randomized Trial * Randomized trial is a cohort design with exposure assigned rath...

r3 - 03 Apr 2012 - 23:13 by MaryBanach

Rate and Cumulative Incidence Lead Author(s): Jeff Martin, MD Rate Reserved for Measuring Incidence Rate should be reserved for measuring incidence. * In ge...

r4 - 05 Jun 2009 - 23:41 by MaryB

Measure of Association Rate Ratio Definition of Rate In a cohort study: Rate is based on events per person time = incidence rate We have limited the use of t...

r9 - 04 May 2009 - 23:16 by MaryB

Receiver Operating Characteristic Curve A receiver operating characteristic (ROC) curve is used to make an assessment of the overall value of a new diagnostic te...

r7 - 13 Mar 2011 - 23:55 by ErinEsp

Relational Databases This presentation by Dr. Michael Kohn of UCSF gives a great introduction to the topic, and offers the following guidelines for data managemen...

NEW - 04 Aug 2011 - 19:05 by MaryBanach

Relative RiskAlso called the Risk Ratio.This is a measure of the association between a predictor (or independent) variable and a yes or no (binary) outcome (or de...

r21 - 21 Jun 2012 - 06:03 by PeterBacchetti

Rescaled Predictors In regression models with a numeric predictor, the estimated effect is that associated with a 1 unit increase in the predictor. In some cases,...

r4 - 14 Apr 2009 - 22:30 by CTSpediaAdmin

Listing of Research Topics Need Authors

r3 - 03 Aug 2011 - 20:55 by MaryBanach

Residuals Not Normally Distributed FORUM QUESTION: Main.ErinMadden1 03 Sep 2010 16:20 For a linear regression where the residuals are not normally distribute...

r2 - 05 Aug 2011 - 17:06 by MaryBanach

Risk Factor A risk factor is a variable associated with an increased risk of disease or infection. Risk factors are correlational and not necessarily causal, beca...

r5 - 03 Apr 2012 - 20:26 by MaryBanach

Prevalence of Risk Factor Lead Author(s): Jeff Martin, MD Definition of Prevalence of Risk Factor The prevalence of a risk factor is also important from a publ...

r4 - 02 Jun 2009 - 20:21 by MaryB

Risk Ratio versus Rate Ratio Lead Author(s): Jeff Martin, MD RR Relative risk or RR is very common in the literature, but may represent: * a risk ratio, * ...

r6 - 01 Jun 2009 - 19:41 by MaryB

Measure of Assocation Risk Ratio Lead Author(s): Jeff Martin, MD Definition of Risk In a cohort study: Risk is based on proportion of persons with disease = ...

r21 - 08 Mar 2011 - 21:14 by MaryBanach

Stata Stata is a general purpose statistical software package created in 1985 by StataCorp. It is used by many businesses and academic institutions around the wor...

r9 - 04 Aug 2011 - 19:15 by MaryBanach

Case Control Design Sampling at Baseline Special type of case control study: Case cohort design Lead Editor(s): Jeff Martin, MD Summary of Case Control Sampli...

r26 - 29 May 2009 - 18:26 by MaryB

Case Control Design Sampling Controls at Follow up Lead Author(s): Jeff Martin, MD Summary of Case Control Sampling Design Sampling Measure of Associat...

r19 - 04 Apr 2012 - 19:48 by MaryBanach

Case Control Design Incidence Density Sampling CUT Lead Author(s): Jeff Martin, MD Summary of Case Control Sampling DesignSamplingMeasure of Association Ca...

r24 - 05 Jun 2009 - 20:05 by MaryB

Case Control Design Incident Density Sampling Dynamic Primary Study Base Lead Author(s): Jeff Martin, MD Case Control Incidence Density Sampling in a Dynami...

r2 - 01 Jun 2009 - 20:13 by MaryB

Sampling ANCHORS Lead Author(s): Jeff Martin, MD Definition of Sampling * Sampling is the process by which individuals belonging to a larger target population...

r14 - 15 Dec 2010 - 01:49 by MaryBanach

Skewed Variable A skewed variable has a distribution where there are a few observations that are much larger (right skewed) or smaller (left skewed) than the othe...

NEW - 29 Jun 2013 - 05:47 by PeterBacchetti

Standardized Mortality Ratio Standardized Mortality Ratio In the example of petrochemical workers: * If U.S. death rates for age sex race calendar period grou...

r2 - 05 May 2009 - 20:22 by MaryB

Stand Alone Data Entry Main.KnutWittkowski 26 Jun 2009 08:31 Michael, EpiInfo is using MS Access for both the data and the meta data. Do you have any suggest...

r2 - 21 Jun 2012 - 18:32 by MaryBanach

P values Lead Author(s): Peter Bacchetti, PhD These are usually interpreted as showing the strength of evidence against the possibility that there is truly no ass...

r13 - 21 Jun 2012 - 19:08 by MaryBanach

Stata Commands Here are several sites that have Stata commands you may find useful (by no means an exhaustive list): University of Chicago, Department of Statisti...

NEW - 04 Aug 2011 - 19:20 by MaryBanach

Statistical Test Needed FORUM QUESTION: Julia St George 22 May 2009 12:12 I found that 0 of 63 patients responded to an alternative therapy, but when I subm...

r2 - 05 Aug 2011 - 15:28 by MaryBanach

Stratification Lead Author(s): Jeff Martin, MD Definition of Stratification Forming separate strata or groups during study analysis or during study design. #S...

r19 - 15 Dec 2010 - 01:33 by MaryBanach

Study Analysis: 2 x 2 Table or Chi square Test Lead Author(s): Jeff Martin, MD Measuring Association The simplest way to measure the association is to have a dic...

r5 - 05 Jun 2009 - 20:51 by MaryB

Adjustment The method of modifying observations to account for external factors that may distort or skew associations in observations. Adjusted Measure of Assoc...

r13 - 29 Apr 2009 - 19:28 by MaryB

Backwards Strategy Lead Author(s): Jeff Martin, MD Backwards Strategy for Potential Confounders In the Backwards Strategy we initially evaluate all potential co...

r7 - 01 Jun 2009 - 19:47 by MaryB

Bias Variance Tradeoff Lead Author(s): Jeff Martin, MD Bias Variance Tradeoff * What is a meaningful difference between the crude and adjusted measure of ass...

r7 - 18 Jan 2010 - 22:53 by MaryB

Forwards Strategy Lead Author(s): Jeff Martin, MD Forwards Strategy for Potential Confounders In contrast to the backwards strategy for potential condunders t...

r2 - 11 Jun 2009 - 21:55 by MaryB

Inappropriate Statistical Testing for Confounding Lead Author(s): Jeff Martin, MD Examining a Known Confounder Testing for statistically significant differenc...

r10 - 01 Jun 2009 - 19:51 by MaryB

Life Tables Lead Author(s): Jeff Martin, MD Definition of Life Tables Life tables, as the name implies, were first constructed to look at the cumulative surviv...

r3 - 03 Jun 2009 - 17:14 by MaryB

Summary Estimators: Mantel Haenszel Method Lead Author(s): Jeff Martin, MD This is one method for calculating summary adjusted estimators when making adjustments...

r6 - 11 Jun 2009 - 21:53 by MaryB

Model Selection Main.MaryB 21 Apr 2009

NEW - 21 Apr 2009 - 21:16 by MaryB

Adjustment for Multiple Confounders Lead Author(s): Jeff Martin, MD Stratification of Multiple Confounders with More Than Two Levels Stratification can also be...

r8 - 12 Jun 2009 - 18:53 by MaryB

Obtaining the Denominator for Person Time Rates Lead Author(s): Jeff Martin, MD There are two methods for obtaining the denominator for person time rates. Meth...

r7 - 05 Jun 2009 - 23:55 by MaryB

Study Analysis Plan Lead Author(s): Jeff Martin, MD When Written Written before the data are analyzed Study Analysis Plan Content * Detailed description ...

r2 - 03 Jun 2009 - 20:16 by MaryB

Variance Definition of Variance Jeff Martin, MD Main.MaryB 17 Apr 2009

r5 - 22 Apr 2009 - 21:43 by MaryB

Association Lead Author(s): Jeff Martin, MD Definition of Association * Relationship between two or more events or variables. Measuring Disease Association ...

r14 - 03 Feb 2012 - 23:10 by PeterBacchetti

Measure of Association Risk Difference Lead Author(s): Jeff Martin, MD Why Use Risk Difference? Risk difference gives an absolute measure of the association ...

r7 - 02 Jun 2009 - 18:55 by MaryB

Study Base Lead Author(s): Jeff Martin, MD Definition of a Study Base A study base, also called a reference population, is a defined population whose disease exp...

r14 - 02 Jun 2009 - 20:57 by MaryB

Primary Study Base A study base, also called a reference population, is a defined population whose disease experience during some period of time is the source of...

r3 - 15 Sep 2010 - 20:15 by MaryBanach

Secondary Study Base Lead Editor(s): Jeff Martin, MD A study base, also called a reference population, is a defined population whose disease experience during so...

r5 - 15 Dec 2010 - 01:49 by MaryBanach

Cohort Lead Author(s): Jeff Martin, MD Definition of a Cohort Any well defined population can be thought of as a cohort that continues to recruit new subjects...

r6 - 02 Jun 2009 - 21:16 by MaryB

Study Design Strength of design rests on accurate measurements made prior to the outcome, not whether it is cohort or case control sampling Jeff Martin, MD Main...

r2 - 14 Apr 2009 - 22:30 by CTSpediaAdmin

Study Design Elements Study Design Element 1: Identify the Population The first key element in study design that uses observation of individuals is to identify t...

r3 - 30 Apr 2009 - 18:15 by MaryB

Disease Occurrence Lead Author(s): Jeff Martin, MD Measuring Disease Occurrence Occurrence of disease is the fundamental outcome measurement of epidemiology Oc...

r5 - 02 Jun 2009 - 23:24 by MaryB

Incidence Lead Author(s): Jeff Martin, MD Definition of Incidence Incidence counts new disease diagnoses during a defined time period. Incidence vs Prevalence...

r26 - 02 Jun 2009 - 19:13 by MaryB

Cumulative Incidence Person Time Lead Author(s): Jeff Martin, MD Definition of Cumulative Incidence The proportion of individuals who experience the event...

r25 - 03 Jun 2009 - 17:15 by MaryB

Incidence Rate Using Person Time Lead Author(s): Jeff Martin, MD Definition of Incidence Rate Using Person Time The number of events divided by the amount of p...

r17 - 02 Jun 2009 - 20:39 by MaryB

Measurement Definition of Measurement Main.MaryB 20 Feb 2009

r2 - 14 Apr 2009 - 22:30 by CTSpediaAdmin

Prevalence Lead Author(s): Jeff Martin, MD #PrevalentTerm Definition of Prevalence Prevalence counts existing disease diagnoses, usually at a single point in ti...

r14 - 02 Jun 2009 - 19:00 by MaryB

Period Prevalence Lead Author(s): Jeff Martin, MD Definition of Period Prevalence Period prevalence is the number of persons with a specific disease at one ...

r4 - 02 Jun 2009 - 19:14 by MaryB

Point Prevalence Lead Author(s): Jeff Martin, MD Definition of Point Prevalence Point prevalence is the number of persons with disease in a time interval (eg...

r3 - 02 Jun 2009 - 19:28 by MaryB

When Is Study Done? Lead Author(s): Jeff Martin, MD Prospective and Retrospective Prospective and retrospective refer to when the study is done in relation to th...

r3 - 02 Jun 2009 - 21:06 by MaryB

Interaction Effect Modifier Lead Author(s): Jeff Martin, MD Definition of Interaction When the magnitude of a measure of association * between exposure and di...

r15 - 02 Jun 2009 - 20:51 by MaryB

Matching Lead Author(s): Jeff Martin, MD Definition of Matching Definition of Matching: * Match unexposed or non case subjects to those of the comparison ...

r8 - 03 Jun 2009 - 22:38 by MaryB

Randomization Definition of Randomization Definition of Randomization: random assignment of subjects to exposure (e.g., treatment) categories One of the three...

r3 - 14 Apr 2009 - 22:30 by CTSpediaAdmin

Restriction Lead Author(s): Jeff Martin, MD Definition of Restriction Definition of Restriction: Restrict enrollment to only those subjects who have a specific...

r4 - 01 Jun 2009 - 20:11 by MaryB

Unit of Observation Lead Author(s): Jeff Martin, MD Study design begins with the unit of observation( note diagram). Either the observations are: * Made on i...

r6 - 05 Jun 2009 - 23:57 by MaryB

r2 - 04 Aug 2011 - 21:36 by MaryBanach

Type 3 p value This is a p value for the composite null hypothesis that all levels of a categorical predictor have the same effect on the outcome as the reference...

r7 - 04 Apr 2012 - 19:55 by MaryBanach

Validity Lead Author(s): Jeff Martin, MD Types of Validity There are two types of validity: * Internal : Inference from the study sample to the source populat...

r7 - 15 Dec 2010 - 01:49 by MaryBanach

External Validity or Generalizability Lead Author(s): Jeff Martin, MD What is External Validity or Generalizability? External validity is a measure of how well ...

r4 - 11 Jun 2009 - 21:06 by MaryB

Measurement Validity Sensitivity Lead Author(s): Jeff Martin, MD What Is Sensitivity? Sensitivity is the ability of a measurement to identify correctly those...

r4 - 01 Jun 2009 - 21:30 by MaryB

Measurement Validity Specificity Lead Author(s): Jeff Martin, MD What Is Specificity? Specificity is the ability of a measurement to identify correctly those...

r4 - 01 Jun 2009 - 21:31 by MaryB

Internal Validity Lead Author(s): Jeff Martin, MD What Is Study or Internal Validity? Study validity is what we refer to as internal validity or a measure of how...

r7 - 12 Jun 2009 - 17:45 by MaryB

Value Column Lead Author(s): Jeff Martin, MD In output from regression modeling macros, this gives the particular level of a categorical predictor that the result...

r4 - 03 Jun 2009 - 20:04 by MaryB

Constant or Fixed Variable Lead Author(s): Definition of a Constant Variable Definition of a Fixed Variable

r3 - 01 Jun 2009 - 21:22 by MaryB

Intermediary Variable Lead Author(s): Intermediary Variable Is Not a Confounder As seen in the diagram below a variable that is an intermediate step in the causa...

r11 - 03 Jun 2009 - 19:56 by MaryB

Third Variable: Intermediate, Effect Modifier, Confounder or No Effect Lead Author(s): Jeff Martin, MD Third Variable When evaluating association between an expo...

r15 - 03 Jun 2009 - 20:02 by MaryB

Variable Column Lead Author(s): Peter Bacchetti, PhD In output from regression modeling macros, this column gives the name of the predictor or independent variab...

r5 - 12 Jun 2009 - 18:44 by MaryB

Variance Inflation Factor

r2 - 14 Apr 2009 - 22:31 by CTSpediaAdmin

Web based Interactive System for Study Design, Optimization and Management (WISDOM) WISDOM for Web based Interactive system for Study Design, Optimization, and M...

r5 - 27 Oct 2011 - 17:09 by MaryBanach

Number of topics: 246

Searched: parent.name = 'ContentInterest'

Analysis of Variance Lead Author(s): Main.NancyHills The term analysis of variance (ANOVA) describes a group of inferential statistical tests that were developed...

r3 - 01 Aug 2011 - 17:46 by MaryBanach

Common Biostatistical Problems 1 P values for establishing negative conclusions 1 Misleading and vague phrasing 1 Speculation about low power 1 Exclu...

r15 - 13 Jul 2012 - 04:52 by PeterBacchetti

Correlation Lead Author(s): Main.NancyHills Measures of correlation are not statistical tests of inference, but are actually descriptive statistical measures whic...

r5 - 01 Aug 2011 - 17:39 by MaryBanach

Estimation versus Hypothesis Testing Lead Author(s): George Howard, DrPH Inference ESTIMATION Statistics in Estimation Repeated Estimates Uncertainty in ...

r7 - 21 Jun 2012 - 21:43 by MaryBanach

Geocoding: What is it and why is it necessary? This article is derived from materials created by Dr. David Rehkopf. Geocoding involves assigning an exact location...

r4 - 01 Aug 2011 - 17:43 by MaryBanach

Avoiding Insufficient or Excessive Precision How many decimals to give is a common practical issue in reporting the results of statistical analyses in publication...

r2 - 05 Oct 2014 - 20:45 by PeterBacchetti

Infinite Estimates Lead Author: Peter Bacchetti, PhD Some regression methods, notably logistic regression and Cox proportional hazards regression, can produce de...

r4 - 10 Jun 2014 - 20:36 by PeterBacchetti

Interval Censored Survival Analysis Primary Author: Main.JohnKornak Description Survival analysis methods play an important role in the statistical analysis of...

r2 - 03 May 2013 - 21:42 by PeterBacchetti

Career Development Awards, K Series Lead Author: Tom Mitchell Types of Mentored Career Development Awards * There are a number of different mentored K awards ...

r8 - 01 Aug 2011 - 17:51 by MaryBanach

Logarithmic Transformation Lead Author(s): Peter Bacchetti, PhD Statistical models are sometimes more meaningful and accurate if outcome or predictor variables ...

r6 - 12 Jun 2013 - 18:05 by PeterBacchetti

Longitudinal Cohort Studies Lead Author(s): Jeff Martin, MD A longitudinal study is a correlational research study that involves repeated observations of the same...

r7 - 03 Apr 2012 - 23:56 by MaryBanach

Common Biostatistical Problems and the Best Practices that Prevent Them This is based on Peter Bacchetti's lecture on "Common Biostatistical Problems and the Bes...

r34 - 11 Mar 2014 - 01:57 by PeterBacchetti

Main.PeterBacchetti 16 Jun 2012 In a study of how long participants survive or how long they go without experiencing a particular event of interest, fully describ...

r2 - 04 May 2013 - 00:01 by PeterBacchetti

Reporting Power Lead Author(s): Peter Bacchetti, PhD Power calculations are widely recognized to be irrelevant in the interpretation of completed studies, becaus...

r4 - 29 Mar 2013 - 21:59 by PeterBacchetti

Proper Interpretation of Results Lead Author: Peter Bacchetti, PhD This page provides general conceptual guidance on interpreting results of statistical analyses ...

r28 - 12 Feb 2012 - 01:13 by PeterBacchetti

Current Sample Size Conventions: Flaws, Harms, and Alternatives This is a CTSpedia version of an open access article originally published as: Bacchetti P. Curren...

r8 - 24 Jan 2014 - 22:19 by PeterBacchetti

Under Construction Significance Testing as Perverse Probabilistic ReasoningThis is a CTSpedia version of an open access article originally published as:Westover M...

r2 - 08 Mar 2012 - 02:31 by PeterBacchetti

Use of Significant Alone in Publications Do not use the word significant alone in scientific publications that include statistical analysis. This term is ambi...

r2 - 05 Oct 2014 - 20:35 by PeterBacchetti

Computer Assisted Interviewing Software Lead Editor(s): Main.NicolasSheon The two main reasons for using a computer to administer a survey are efficiency (no need...

r4 - 01 Aug 2011 - 17:47 by MaryBanach

Statistical Computing and Graphics Concepts to Master 1 Difference between a functional language with live access to data and a procedural or macro language ...

r2 - 11 Aug 2011 - 17:47 by MaryBanach

Common mistakes when describing a study population (the typical Table 1) Reports of both observational and experimental studies typically include descriptive summ...

r4 - 30 Jun 2014 - 20:18 by DalePlummer

Using a National Database Leading Author(s): Yolanda Hagar Helpful Tips, Hints and Things to Consider Using a national database can be very advantageous. The pri...

r3 - 01 Aug 2011 - 17:49 by MaryBanach

Number of topics: 22

- CompositeNullHypothesis
- ControlGroupDefinition
- DescriptiveStudy
- EffectDef
- LimitationsOfOmnibus
- LinearityAssumption
- MisclassSpecColl
- MisclassSpecTest
- MultiVariateAnalysis
- OmnibusTest
- OutcomesDef
- PowerDef
- PowerTerm
- ProbabilityTerm
- ProportionalHazardModel
- SampleSize
- SamplingError
- StudyAnalysisMultivariate
- StudyCase
- StudyControl
- StudyTime
- StudyTimeClose
- SurvivalAnalysis

Number of topics: 23