The Students ttest Test to determine differences between

The Student’s t-test Test to determine differences between two samples

Topics �Data assumptions before computing for t-test or Mann-Whitney U Test �Student’s t-test �T-test Defined �Example of t-test �Applications of the t-test

Student’s t-test History �Introduced in 1908 by William Sealy Gosset (pen name “Student”), a chemist working for the Guinness brewery in Dublin, Ireland �Gosset devised the t-test as a way to cheaply monitor the quality of stout (a dark beer) �He published the test in Biometrika in 1908, but was forced to use a pen name by his employer because they were using statistics as a trade secret �Gosset's identity was unknown to fellow statisticians

Purpose of t-test �Used to test for significant differences between two sets of data or two groups �Based on a comparison of means �Appropriate whenever you want to compare the means of two groups �Especially appropriate as the analysis for the posttestonly two-group randomized experimental design

Illustration of the t-test

Formula for the t-test

Detailed Formula

Example of the t-test

Student’s t-table

How to state the conclusion �If there is a significant difference �The data presents sufficient evidence that there is a significant difference between Group I and Group II. �If there is no significant difference �The data does not present sufficient evidence that there is a significant difference between Group I and Group II. �If about post-test difference, �The data presents sufficient evidence that there is a significant difference between the treatment group and the control group.

Group Work �Identify variables within the class that can be subjected to the t-test and undertake the data gathering �Present the results