When Should Independent or Dependent T-Tests be Used?

Independent and dependent t tests are similar, but comparing two different groups and two groups with repeated measures (i.e., pre- or post-testing) serve very different purposes.

For this discussion, develop an original response proposing two hypothetical scenarios, as follows:

Name a dependent variable you could compare, for both an independent and dependent t test. (Do not use the variables in the Sample Dataset you are using for assignments.)

The independent t test should compare the dependent variable between two groups (i.e., divided by race, gender, socioeconomic class, or some other factor).

The dependent t test should be conducted on the same group (same sample, same data) where the dependent variable is measured twice (pre- and posttest).

The above is what the discussion is based on:

Respond to the following post in one paragraph each

Post 1

The independent t-test, also known as the two-sample t-test, is a statistical test used to compare the means of two independent groups or samples. It is appropriate to use when you want to determine whether there is a statistically significant difference between the means of two populations based on the data collected from these groups. To perform an independent t-test, you need to have two independent groups, a continuous outcome variable, and assume that the data within each group are approximately normally distributed. Additionally, the variances of the two groups should be approximately equal, although the independent t-test can still be robust to violations of this assumption in certain situations (e.g., if the sample sizes are large and approximately equal). It is always important to carefully consider the assumptions and requirements of the independent t-test before applying it to your data. If these assumptions are not met, alternative tests or data transformations may be more appropriate. Thoughts?

Post 2

Student engagement is at the center of many instructional endeavors. Research about what impacts student engagement helps illustrate the benefits of using independent and dependent research tests. While they both have benefits to research, their purposes are very different.

In a research study in which researchers study the impact of a new technology tool, researchers might survey students about the level of engagement they experience with instruction that includes the new tool. The dependent variable in this hypothetical scenario is the student self-assessment of engagement level. A dependent variable is a variable whose value is an assessment of any change or manipulation being studied (Wagner & Gillespie, 2019). This dependent variable could be compared for both an independent and dependent t test. An independent t test example would be a comparison of two groups, one group of students whose teacher used the new technology tool in instruction and one group of students whose teacher did not use the new technology tool. In the same scenario, the researcher could also use a dependent t test. In this scenario, the same group would be surveyed before and after instruction with the new technology tool.

Post 3

For this discussion module will be proposing two hypothetical scenarios

Scenario 1:

Dependent variable: FAST (Florida Assessment Standardized Test) scores

Independent variable: Socioeconomic class

In scenario 1, the dependent variable is the FAST scores which is what we will be trying to measure. The American College of Education (2023) explains that the independent variables are also named control variables since they can control or be modified to see their effect on the dependent variable. In this case, the independent variable, socioeconomic class, will be divided into group A (low socioeconomic class) and group B (high socioeconomic class). In the proposed study, we can test the difference in the FAST scores according to students belonging in group A versus group B.

Scenario 2:

Dependent variable: Stress levels

Independent variable: Rethink app training in school (mindfulness)

In scenario 2, the dependent variable is the anxiety and stress levels experienced by high school students. The stress level will be determined by a Likert scale. The independent variable will be the lessons from the Rethink app showing mindfulness videos and activities for high school students. In this research, the students received a Likert scale before the trainings (pretest) and one after the trainings (posttest) to determine the effectiveness of the lessons and activities provided by the Rethink app.