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Example of a Dependent-Samples -Test: Calorie Estimation
To illustrate a dependent-samples -test, consider a pretest-posttest study evaluating a training program designed to improve calorie estimates. A sample of 10 participants estimates calories in a cookie both before and after the training. Subtracting the pretest estimates from the posttest estimates yields a set of 10 difference scores with a mean () of 8.50 and a standard deviation () of 24.27. Using the one-sample -test formula on these difference scores against a hypothetical population mean of 0, the computed score is 1.11. For a one-tailed test with 9 degrees of freedom (10 - 1), the critical value is 1.833. Because the calculated score (1.11) is less extreme than this critical value, the researcher fails to reject the null hypothesis, concluding that the training program does not significantly increase calorie estimates. The corresponding -value is .148, which is greater than the standard .05 alpha level.
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Research Methods in Psychology - 4th American Edition @ KPU
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Repeated Measures Designs
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When is it most appropriate to use a dependent-samples t-test in a research study?
A cognitive psychologist measures the reaction times of 40 participants while they complete a task in a quiet room, and then measures the reaction times of those exact same 40 participants while they complete the task in a noisy room. The psychologist should use a dependent-samples t-test to analyze the differences in reaction times.
Match the following terms associated with the dependent-samples -test to the description that best captures their conceptual role in psychological research.
A psychologist is conducting a within-subjects study where participants' memory performance is measured both before and after a specific intervention. To perform a dependent-samples -test on this data, the researcher must transform the paired scores into a testable format. Arrange the following steps in the correct logical order of analysis.
The dependent-samples -test is also commonly referred to as the paired-samples -test.
In a within-subjects psychology experiment, a researcher uses a dependent-samples -test to analyze the data. Which of the following best explains the conceptual logic of how this test processes the participants' scores from two different conditions?
A researcher is critiquing a study that measured 30 participants' reaction times before and after a specific cognitive intervention. The researcher argues that the original analysis was flawed because it failed to account for the fact that the two sets of scores are not independent. To correctly evaluate this pretest-posttest data and account for the systematic relationship between the measurements, the researcher should have used a(n) _____-samples -test.
A researcher is planning a study and must select the appropriate statistical test. Match each research scenario to the correct conclusion about whether a dependent-samples t-test is appropriate and why.
The dependent-samples t-test is conceptually a special case of the one-sample t-test because it first computes a _____ for each participant by subtracting one of their scores from the other, and then tests whether the mean of those computed values is significantly different from zero.
A graduate student is reviewing a peer's research report that claims a dependent-samples t-test was the correct statistical analysis for the study. Order the steps the graduate student should follow to evaluate whether that claim is justified.
Define the dependent-samples -test and state its alternative name. Under what two research designs is this statistical test particularly appropriate, and how does it function conceptually in relation to another type of -test?
Explain why a dependent-samples -test is the appropriate choice for analyzing the difference in mean estimation accuracy in this scenario, and describe how this test conceptually functions in relation to a one-sample -test.
A cognitive psychologist is conducting a within-subjects experiment to compare how participants perform on a reading task under two distinct conditions: once with background music playing, and once in silence. Identify the specific statistical test they should use to compare the performance means under these two conditions and apply the conceptual definition to justify this choice.
Example of a Dependent-Samples -Test: Calorie Estimation
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In the calorie-estimation pretest-posttest example, what is the computed score for the dependent-samples -test?
In a dependent-samples -test, a researcher fails to reject the null hypothesis when the computed score is less extreme than the critical value, indicating the result is not statistically significant.
Match each value or outcome from the calorie-estimation dependent-samples -test example to its correct role or interpretation in the analysis.
In the provided example, the researcher evaluates the effectiveness of the training program by comparing the computed score (1.11) to the critical value (1.833). Because the calculated score is less extreme than the critical value, the researcher fails to reject the _____ hypothesis.
Order the steps a researcher must perform and evaluate to determine if the calorie-estimation training program is statistically significant, from the initial calculation of difference scores to the final hypothesis decision.
In the provided pretest-posttest study evaluating the training program, what is the critical value for the one-tailed dependent-samples -test with degrees of freedom?
Explain how a dependent-samples -test reduces pretest and posttest scores to a single set of difference scores. In your explanation, describe what a hypothetical population mean of represents in the context of evaluating the effectiveness of the training program.
Based on the provided statistical results, decide whether the researcher should reject or fail to reject the null hypothesis, and justify what this decision means regarding the effectiveness of the training program.
In the calorie-estimation study, the standard deviation () of the difference scores is 24.27 with a mean () of 8.50. If the standard deviation had been much smaller (e.g., 5.00) while the mean difference () and sample size () remained the same, analyze how this change would affect the standard error, the computed score, and the final hypothesis decision.