The procedures additionally provide tests of assumptions about variation and the distribution.
In addition to providing the p-value information for the appropriate test, the T-test procedures in NCSS also provide confidence intervals for means or differences, confidence intervals for the variation, z-tests, power reports, and nonparametric analogs to the tests, such as randomization tests, the quantile (sign) test, the Wilcoxon Signed-Rank Test, the Mann-Whitney test, and the Kolmogorov-Smirnov test. Two-Sample T-Test from Means and Standard Deviations.The T-test procedures available in NCSS include the following: T-tests are very useful because they usually perform well in the face of minor to moderate departures from normality of the underlying group distributions. The T-test is a common method for comparing the mean of one group to a value or the mean of one group to another. There you will find references, formulas, discussions, and examples/tutorials describing the procedure in detail. If you wish to see the formulas and technical details relating to a particular NCSS procedure, click on the corresponding '' link under each heading to load the complete procedure documentation. This page is designed to give a general overview of the capabilities of NCSS for the comparison of means. In our NCSS software, we seek to provide these tools in a concise and accurate manner, with straightforward output and to-the-point graphics. The general goal for most of these tools is to use the estimate of the mean (or other central measure), assess the variation based on sample estimates, and use this information to provide the amount of evidence of a difference in means or central tendency. For cases where some assumptions are not met, a nonparametric alternative may be considered.
Common statistical tools for assessing these comparisons are t-tests, analysis-of-variance, and general linear models.
Multivariate Analysis of Variance (MANOVA)Ī common problem that arises in research is the comparison of the central tendency of one group to a value, or to another group or groups.To see how these tools can benefit you, we recommend you download and install the free trial of NCSS. Use the links below to jump to the comparison of means topic you would like to examine. Comparing Means in NCSS The group of tools for comparison of means constitute a very large portion of the common statistical tasks required in research. NCSS Statistical Software contains a variety of tools for tackling these tasks that are easy-to-use and carefully validated for accuracy.
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