Basic Concepts
We now consider an experimental design to determine whether there is a difference between two groups within the population. For example, suppose we want to test whether a new drug is effective in treating cancer. One approach is to create a random sample of 40 people, half of whom take the drug and half take a placebo. For this approach to yield valid results it is important that people be assigned to each group at random. Such samples are independent.
Provided the assumptions are met, a two-independent sample t-test is usually employed in these situations.
Topics
- Two Sample t-test: equal variances
- Two Sample t test: unequal variances
- Assumptions for Two-Sample t-Test
- Two Sample Effect Size
- Real Statistics two-sample t-test data analysis tool
- Multiple t-Tests
- Two Sample t-Test Proof
Reference
Howell, D. C. (2010) Statistical methods for psychology (7th ed.). Wadsworth, Cengage Learning.
https://labs.la.utexas.edu/gilden/files/2016/05/Statistics-Text.pdf