# Student's t-test

There are many textbooks and websites available that give a theoretical discussion of the t-distribution, its usefulness, and precautions that should be exercised when using the t-distribution for statistical inference. Most spreadsheet programs and many calculators have built-in statistical functions that readily access relevant statistical information.

Mathworld provides a generic discussion of the t-distribution. The links below not only give overviews of the t-distribution but also have online interactive routines for calculating relevant t-distribution statistics.

- Use Compute CI button to calculate confidence limits of a sample mean using mean, standard deviation, and sample size on this interactive site from Texas A&M University
- Confidence Interval is a JAVA simulator that can help students better understand the meaning of confidence interval.
- t-test from College of Saint Benedict Saint John's University Physics Here is an example pdf file (Acrobat (PDF) 81kB Jul29 04) that graphically shows the data, the t-distribution for each sample, and the output tables generated from this t-test site.

**Other References**

- An excellent text on statistical applications with many clear numerical examples. G.S. Snedecor and W.G.Cochran, 1989. Statistical Methods, Eight Edition fro the Iowa University Press.
- Hyperstat (more info) has a good basic discussion of the estimate confidence intervals for correlation and regression.
- Compare Normal and t-distributions with this calculator
- The discussion Presenting Data (more info) provides a good overview of error bars.