PSY t-Test Application and Interpretation

Instructions

Complete the following for this assignment:

• You will complete this assignment using the Data Analysis and Application template (DAA Template [DOC]).
• Refer to IBM SPSS Step-by-Step Guide: t Tests [DOC] for additional information on using SPSS for this assignment.
• If necessary, review the Copy/Export Output Instructions [HTML] to refresh your memory on how to perform these tasks. Your submission should be in narrative format with supporting statistical output (table and graphs) integrated into the narrative in the appropriate places (not all at the end of the document).
• As you work on this assignment, you may find the Data Set Instructions [DOC] helpful.

You will analyze the correlations among the following variables in the grades.sav data set:

• gender.
• gpa.

Step 1: Write Section 1 of the DAA: The Data Analysis Plan.

• Briefly describe the goal of your analysis.
• State your research question, null, and alternate hypothesis.
• Specify the variables used in this analysis (predictor, outcome) and the scale of measurement of each variable.
• State the sample size (N) and the alpha level you will use (.05 unless otherwise specified).
• Explain why the analysis is a good choice based on the nature of your variables.

Step 2: Write Section 2 of the DAA: Testing Assumptions.

• Articulate and test the assumptions of the t test.
• Paste the SPSS histogram output for each variable and discuss your visual interpretations.
• Paste SPSS descriptives output showing skewness and kurtosis values and interpret them.
• Paste the SPSS descriptives output showing skewness and kurtosis values for gpa and interpret them.
• Paste the SPSS output for the Shapiro-Wilk test of gpa and interpret it.
• Report the results of the Levene test and interpret it.
• Analyze whether the assumptions of the t test are met. If assumptions are not met, discuss how to ameliorate violations of the assumptions.

Step 3: Write Section 3 of the DAA: Results and Interpretation.

• Paste the SPSS output of the t test. Include the following:
  • t.
  • Degrees of freedom.
  • p value.
  • Effect size.
  • Interpretation of effect size.
  • Means and standard deviations for each group.
  • Mean difference.
  • 95% confidence interval of the difference of sample means.
• Interpret statistical results against the null hypothesis and state whether it is accepted or rejected.

Step 4: Write Section 4 of the DAA: Statistical Conclusions.

• Provide a brief summary of your analysis and the conclusions drawn.
• Analyze the limitations of the statistical test.
• Provide any possible alternate explanations for the findings and potential areas for future exploration.

Step 5: Write Section 5 of the DAA: Application.

• Analyze how you might use this statistical approach in your field and what the potential implications would be.

Readings

Read about how to apply your knowledge of t tests and run some analyses in SPSS.

• George, D., & Mallery, P. (2019). IBM SPSS statistics 25 step by step: A simple guide and reference (15th ed.). New York, NY: Routledge.
  • Chapter 11, pages 149–158, describes how to run a t test in SPSS.
• Field, A. (2018). Discovering statistics using IBM SPSS: North American edition (5th ed.). Thousand Oaks, CA: Sage.
  • Review Chapter 10’s information on t test assumptions and comparing independent means to help you with your assignment.
• The 7864 Course Study Guide [PDF] highlights content to focus on as you read and absorb the materials. You may also find some additional articles with direct relevance to your field here.