# SIMSTAT: Summary

Using SIMSTAT for statistical analysis
SIMSTAT provides most of the simple statistical tests and procedures that you will ever need. One exception is nonlinear regression, which can lead to non-unique results and which should therefore be performed (except for ARIMA and time series) using one of the dedicated Simfit nonlinear fitting programs. Many of the procedures provided by SIMSTAT are also available for experienced users but with more help and advice, and sometimes with additional options, as dedicated individual programs. For example, program LINFIT can be used for robust regression as well as for linear and multilinear regression. You can prepare your data in files like the test files supplied with the Simfit package, but many users prefer to keep their spreadsheet program open at the same time as Simfit and simply transfer data as required using the clipboard. Whenever a data file is requested by Simfit the clipboard is inspected and, if the clipboard contains a data table, the Paste button becomes activated so you can paste the data directly into Simfit. You can inspect the clipboard data at any time from the main Simfit [View] menu.

Preparing data
The Simfit package has a special set of editors to allow you to create or edit data files for statistical analysis. If you use these editors your data will always be correctly formatted and will never be lost by overwriting. These editors have numerous special features and powerful options for manipulating data and graphs, and you are recommended to use them. Often, however, users already have their data in the form of tables in spreadsheet programs, so Simfit can analyse tables pasted from the clipboard or create correctly formatted files from clipboard data. Users of Microsoft Excel can create files in the Simfit format directly from Excel by using the Simfit macros called Simfit?.xls, e.g. Simfit4.xls. These are loaded into Excel and can be activated to create files in the Simfit format from data columns that you select by highlighting.
To analyse a single sample you need a column (i.e. vector) of data in the correct format. This can be typed in from the terminal or pasted in from the clipboard, but the best way is to make a vector file either by using program MAKMAT or by pasting clipboard data into program MAKSIM.
To analyse two or more samples simply requires a set of such files but, for most procedures involving several vectors, it is much better to create a library file using program MAKLIB, so that a whole group of files can be selected by reading in just one library file.
Where all the columns are of the same length, as in contingency table analysis or when exploring multiple correlations, it is possible to prepare a matrix file by using program MAKMAT, or by pasting a selected table from the clipboard directly into SIMSTAT, or into a file using program MAKSIM. You can, however, use a library file for most matrix calculations, except for contingency table analysis, the Fisher exact test and linear algebra calculations.

Test files
The Simfit package has a set of test files so you can try with data known to be appropriate before trying with your own data. These are referred to when the individual analytical procedures are described. To analyse test data just select the Demo button when data input is requested.

Missing data
Files supplied to SIMSTAT can have no missing values. These must be replaced by substituted values, using your own scheme or one of the methods provided by the Simfit package.

SIMSTAT options

- Data exploration: choose this option when you want to investigate vectors or matrices for means, medians, variances, appearance when plotted, etc.
- Standard statistical tests: choose this option when you want to perform tests on data such as Kolomorov-Smrirnov tests, Mann-Whitney U tests, t tests, chi-square tests, tests for a normal distribution, etc.
- Analysis of variance: choose this option when you want to investigate sets of continuous variables.
- Analysis of proportions: choose this option when you want to investigate sets of discrete variables.
- Multivariate statistics: choose this option for correlation analysis, to create dendrograms, calculate principal components, or compare groups using MANOVA, or canonical variates.
- Regression and calibration: choose this option if you want to fit a line to data, prepare a standard curve for calibration, fit a polynomial, do multilinear regression, or fit a dose response curve for EC50 or LD50, etc.
- Generalized linear models: choose this option for logistic regression, binary logistic regression, or survival analysis with covariates using Exponential, Weibull or Cox models, etc.
- Time series and survival times: choose this option to analyse data obtained as a sequence of measurements at equal time increments and you want to do data smoothing, estimate autocorrelations or or fit autoregressive integrated moving average models (ARIMA). Survival analysis of data with no covariates is also available.
- Statistical calculations: choose this option when you want to do calculations on exploring the variation in power as a function of sample size when preparing protocols for clinical trials, estimating parameter confidence limits, or generating random numbers.
- Numerical analysis: choose this option when you want to do such procedures as finding zeros of polynomials, eigenvalues, determinants, inverses, singular value decompositions of matrices, matrix factorisations or solving linear equations,

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