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Title: Power and Effect Size

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Type of Tool SAS Macro
Title Power and Effect Size
Programmer/Email RuiChen
Contributing Site Rochester
Description This program computes detectable Effect Size for a pre-specified power or for a pre-specified effect size between two treatment conditions within a longitudinal setting (e.g. Diggle, Liang and Zeger, 1994), assuming equal sample sizes and unequal standard deviations for two groups AND provides effect size difference estimates for real study data

Effect size is defined as in Cohen (1988): ef = (mu1 - mu2)/ sqrt[(var1 + var2)/2]
Example Example code
Classification Graph Type
References
Datasets
Data
Software Program SAS
Software SAS
Macro Parameters alpha = significant level
Power = detectable power (if this value is specified, the macro is used to calculate the effect size difference for a given power. otherwise, leave it blank.)
EFD = detectable effect size difference (if this value is specified, the macro is used to calculate the power for a given effect size difference. otherwise, leave it blank.)
Nrep = number of repeated measures in f/u assessments;
Ngrp1 = sample size for group 1 (= sample size for group 2);
Test = 1 or 2, where 1 = one-sided test; 2 = two-sided test
CorrCoef = correlation coefficient;
MissRate = missing rate over entire study period;
startp = 0.01; change this value if error appears in the log file;
R-Code - Attachment
R-Code
SAS-Code - Attachment Rochester_Power Effect Size_Main Macro
SAS-Code
Stata-Code - Attachment
Stata-Code
Other Code - Attachment
Other Code
Called Data Manipulation
Called Tool/Utility
Called Checking Macro
Called Other
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Example Code SAS Example Code
Example Output
SAS Examples
SAS_Example_Code Rochester_Power Effect Size_SAS Example Code
SAS_Example_Output
R Examples
R_Example_Code
R_Example_Output
Stats Examples
Special Features
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Notes1-Legend Section with calls to needed macros
Notes1
Notes2-Legend Macro call with fully specified parameters
Notes2
Notes3-Legend Section with definitions of global macro parameters
Notes3
Notes4-Legend Section with definitions of local macro variables
Notes4
See Also Nested Power Effect Size
Checklists
Stat Tools Disclaimer This SAS macro is developed by Xin Tu and Rui Chen in the Department of Biostatistics and Computational Biology at the University of Rochester under the auspice of the CTSA BERD with the intent to facilitate data analyses and reporting in clinical and related research. It is copyrighted by Dr. Tu, March, 2010 and distributed for free public access.
Discliamer The views expressed within CTSpedia are those of the author and must not be taken to represent policy or guidance on the behalf of any organization or institution with which the author is affiliated.
Permission Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF ERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT OLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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This topic: CTSpedia > WebHome > StatToolsHome > StatToolsTopic019
Topic revision: 06 Apr 2012, MaryBanach
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