In the category of Research & Program Evaluation on the National Counselor Examination (NCE), the Counselor Preparation Comprehensive Examination (CPCE), or another counseling exam, you’ll most likely come across or need to be aware of the idea behind t-Tests.
This video will cover t-tests, one-tailed and two-tailed tests, as well as dependent t-tests and independent t-tests. We also discuss t-values, t-tables, and what a critical t is.
What is a t-test? A t-test—or student’s t—is the simplest version of an analysis of variance, or ANOVA. A t-test is used to compare the mean of two normally distributed samples.
What is a bell curve? Normal distribution is often shown as a “bell curve”, and when we compare two groups with this distribution, a t-test is used to determine if there is significant difference between the mean of these groups.
What is the mean? As a reminder, the mean is the average. Therefore, a t-test will show if there is a significant difference in the average between two groups.
What is a correlated t-test? A correlated t-test is sometimes called a dependent t-test. When the same group is assessed on two occasions, that’s when a correlated t-test would be used. For example, if a group is measured before they take a class and after they take a class, a dependent (or correlated) t-test could be used.
What is a uncorrelated t-test? If it is not the case that you are comparing the same group at two different times, then you would use an uncorrelated t-test, sometimes called an independent sample t-test.
What is a two-group research design? You might also hear about a “two-groups” or “two-randomized-groups” research design. This is referring to a design that compares if the two means are different in a way that is statistically significant, or simply due to chance.
What is a one-tailed t-test? With a one-tailed t-test, the area of rejection would be on one end of the bell curve or the other.
What is a two-tailed t-test? With a two-tailed t-test, the area of rejection would be on both ends of the bell curve (or the normal distribution). See a graphic on the next slide.
What is a t-value? Once a t-test is computed, it will provide or yield a t-value. In other words, the t-value could be thought of as the result.
What is a t-table? The t-table is a reference of critical t values. Most statistics texts will include a t-table, which lists the critical t values in the distribution.
What is the critical t? When you compute a t-test and receive a t-value, you will then compare this to the t-value on a t-table. The value on the t-table is what would be called the critical t.
