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Tuesday, December 23, 2008

The Dependent Samples t-test or the Paired Samples t-test

What is a dependent samples t-test or a paired samples t-test?

One of the most common statistical test, a dependent samples t-test, or a paired samples t-test, is used to find significant mean differences between two groups on a particular measure like SAT scores, ACT scores, GPA, height, or weight. In the case of the dependent samples t-test or a paired samples t-test, the groups of interest are related somehow as siblings or in the environment of a pretreatment vs. posttreatment setting. Either way, the two groups being compared are related somehow. Get help with dependent samples t-test


What is the difference between a dependent samples t-test or a paired samples t-test and an independent samples t-test?

Both tests are used to find significant differences between groups, but the independent samples t-test assumes the groups are not related to each other, while the dependent samples t-test or paired samples t-test assumes the groups are related to each other.

If you're familiar with the tests, a dependent samples t-test or paired samples t-test would be used to find differences within groups, while the independent samples t-test would be used to find differences between groups. Get help with dependent samples t-tests or independent samples t-tests


In a dependent samples t-test or a paired samples t-test, what is the independent variable and what is the dependent variable?

The independent variable and the dependent variable is the same in both the dependent samples t-test and the independent samples t-test. The variable of measure of the variable of interest is the dependent variable and the grouping variable is the independent variable. Get help with dependent samples t-test


Example of dependent samples t-test or a paired samples t-test

The most common use of the dependent samples t-test is in a pretreatment vs. posttreatment scenario where the researcher wants to test the effectiveness of a treatment.

  1. The participants are tested pretreatment, to establish some kind of a baseline measure
  2. The participants are then exposed to some kind of treatment
  3. The participants are then tested posttreatment, for the purposes of comparison with the pretreatment scores

Having both pretreatment scores and the posttreatment scores for the same participants allows us to measure the effectiveness of the treatment, ceteris paribus. Get help with dependent samples t-test