# Wessa.net

http://www.wessa.net/

Wessa.net is an online resource of statistical calculators and forecasting tools.

## Wessa.net offers these software applications free of charge

 Descriptive Statistics Software The Free Statistics Calculator offers a wide range of descriptive and explorative types of statistical measures and analysis: Central Tendency, Average, Mean, Median, Variability, Interquartile Range, Concentration, Lorenz Curve, Gini Coefficient, Skewness, Kurtosis, Quartiles, Percentiles, Notched Boxplot, Histogram, Correlation, Partial Correlation, Rank Correlation (Spearman and Kendall), Simple Regression, Kernel Density Estimation, Harrell-Davis Quantiles, Bivariate KDE, Correlation Matrix, Stem-and-leaf plot, Explorative Data Analysis Multiple Regression Software (R module) Performs Multiple Regression Equation Modeling based on the R language for statistical computing. In future, this module will replace the old C-based version.Several types of regression will be available in future. Statistical Distributions Features Random Number Generators, PPCC Plots (incl. Tukey lambda), and Statistical Distribution Fitting Modules (Maximum Likelihood) for a series of important distributions: Beta, Inverted Beta, Cauchy 1, Cauchy (2 parameters), Chi, Chi Square (1 parameter), Chi Square (2 parameters), Erlang, Exponential, Fisher F, Gamma, Inverted Gamma, Gumbel, Laplace, Logistic, Lognormal, Normal, Pareto, Power, Rayleigh, r-Distribution, Rectangular (Uniform), Student t, Triangular, and Weibull. Statistical Hypothesis Testing Software Offers statistical testing of a variety of hypotheses: Population Mean, Mean (critical value, p-value, type II error, sample size), Skewness/Kurtosis, Quasi Random-Walk Time Series Analysis (R modules) Performs Univariate Box-Jenkins ARIMA modeling, forecasting, and residual model checking. In future this module will replace the old versions based on C code. Statistics Education This section contains various types of Statistics Software for Statistics Education that have been created by Larry Weldon, Simon Fraser University, Vancouver, Canada. Mathematical Equation Plotter Plots mathematical equations, statistical distributions, derived functions, cumulative functions, and apply numerical integration. Equations can be formulated in algebraic form, for instance: y=exp(a*sin(x)+b). The equation is sent through an interpreter and the analysis and equation chart is generated (in .png format). Time Series Database Use this Database to gain access to thousands of time series about financial markets. Note: this application is also available from within our Scientific Forecasting Software. R modules Anyone can create, maintain, and publish R-based modules (subject to editorial acceptance) and make them freely available within the Wessa.net framework. Multiple Regression Software (C module) Performs Multiple Regression Equation Modeling with the following features: Ordinary Least Squares Estimation, Heteroskedasticity tests, Autocorrelation tests, Misspecification tests, Multicollinearity tests, Regression Charts, ANOVA tables, Goodness of Fit, and much more.Several types of regression will be available in future. Scientific Forecasting Software (C modules) Performs Univariate Box-Jenkins ARIMA modeling, forecasting, and various bootstrap simulation methods for the estimation of financial profit density functions according to the following strategies: Buy&Hold, Alexander's Filterrule, truncated Koyck lag-based MACD. Various types of time series analysis tools are available: (Partial) Auto Correlation Function, Spectral Analysis, Variance Reduction Matrix, Standard Deviation-Mean Plot, trimmed Skewness & Kurtosis, suspended rootogram displays, percentiles, concentration, histograms, foreward & backward running autocorrelation, ARMA parameter estimation, and much more. Sample Size Software (sample size, sample accuracy, confidence interval) Factor Analysis (Factor Analysis, Principal Components) Clustering Software (Agglomerative Nesting, Hierarchical Clustering) Reproducible Examples This module provides access to interesting examples that have been published in articles or textbooks together with all the data and statistical software that is needed to reproduce them. All software is readily available online, and the source code of the underlying analysis can be viewed after successful completion. Financial Calculators (currency decimal, currency fraction, present value, future value, Black-Scholes option prices, interest payment, principal payment, number of periods, effective interest, nominal interest, Quasi Random-Walk identification, trading performance statistics, etc...)

## References

• Wessa, P. (2009), Free Statistics Software, Office for Research Development and Education, version 1.1.23-r3, URL http://www.wessa.net/