You will review the theory, logic, and application of t tests. The t test is a basic inferential statistic often reported in psychological research. You will discover that t tests, as well as analysis of variance (ANOVA), compare group means on some quantitative outcome variable.
By successfully completing this assessment, you will demonstrate your proficiency in the following course competencies and assessment criteria:
- Competency 1: Analyze the computation, application, strengths, and limitations of various statistical tests.
- Develop a conclusion that includes strengths and limitations of an independent-samples t test.
- Competency 2: Analyze the decision-making process of data analysis.
- Analyze the assumptions of the independent-samples t test.
- Competency 3: Apply knowledge of hypothesis testing.
- Develop a research question, null hypothesis, alternative hypothesis, and alpha level.
- Competency 4: Interpret the results of statistical analyses.
- Interpret the output of the independent-samples t test.
- Competency 5: Apply a statistical program’s procedure to data.
- Apply the appropriate SPSS procedures to check assumptions and calculate the independent-samples t test to generate relevant output.
- Competency 6: Apply the results of statistical analyses (your own or others) to your field of interest or career.
- Develop a context for the data set, including a definition of required variables and scales of measurement.
- Competency 7: Communicate in a manner that is scholarly, professional, and consistent with the expectations for members in the identified field of study.
- Communicate in a manner that is scholarly, professional, and consistent with the expectations for members in the identified field of study.
Read Assessment 3 Context [DOC] for important information on the following topics:
- Logic of the t test.
- Assumptions of the t test.
- Hypothesis testing for a t test.
- Effect size for a t test.
- Testing assumptions: The Shapiro-Wilk test and Levene’s test.
- Proper reporting of the independent-samples t test.
- t, degrees of freedom, and t value.
- Probability value.
- Effect size.
Read Assessment 3 Context (linked in the Resources) to learn about the concepts used in this assessment.
You will use the following resources for this assessment. They are linked in the Resources.
- Complete this assessment using the DAA Template.
- Read the SPSS Data Analysis Report Guidelines for a more complete understanding of the DAA Template and how to format and organize your assessment.
- Refer to IBM SPSS Step-By-Step Instructions: t Tests for additional information on using SPSS for this assessment.
- If necessary, review the Copy/Export Output Instructions to refresh your memory on how to perform these tasks. As with your previous assessments, your submission should be narrative with supporting statistical output (table and graphs) integrated into the narrative in the appropriate place (not all at the end of the document).
You will analyze the following variables in the grades.sav data set:
Step 1: Write Section 1 of the DAA
- Provide a context of the grades.sav data set.
- Include a definition of the specified variables (predictor, outcome) and corresponding scales of measurement.
- Specify the sample size of the data set.
Step 2: Write Section 2 of the DAA
- Analyze the assumptions of the t test.
- Paste the SPSS histogram output for gpa and discuss your visual interpretations.
- Paste SPSS descriptives output showing skewness and kurtosis values for gpa and interpret them.
- Paste SPSS output for the Shapiro-Wilk test of gpa and interpret it.
- Report the results of the Levene’s test and interpret it.
- Summarize whether or not the assumptions of the t test are met.
Step 3: Write Section 3 of the DAA
- Specify a research question related to gender and gpa.
- Articulate the null hypothesis and alternative hypothesis.
- Specify the alpha level.
Step 4: Write Section 4 of the DAA
- Paste the SPSS output of the t test.
- Report the results of the SPSS output using proper APA guidelines. Include the following:
- Degrees of freedom.
- t value.
- p value.
- Effect size.
- Interpretation of effect size.
- Means and standard deviations for each group. Mean difference.
- Interpret the results against the null hypothesis.
Step 5: Write Section 5 of the DAA
- Discuss the implications of this t test as it relates to the research question.
- Conclude with an analysis of the strengths and limitations of t-test analysis.