T-Test output for assigned variables.

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For this assessment, you will complete an SPSS data analysis report using t-test output for assigned variables.

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:

  • 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.
  • Analyze the decision-making process of data analysis.
    • Analyze the assumptions of the independent samples t-test.
  • Apply knowledge of hypothesis testing.
    • Develop a research question, null hypothesis, alternative hypothesis, and alpha level.
  • Interpret the results of statistical analyses.
    • Interpret the output of the independent samples t-test.
  • 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.
  • Apply the results of statistical analyses to a field of interest or career.
    • Develop a context for the data set, including a definition of required variables and scales of measurement.
  • 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 the Assessment 3 Context document 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.

As you prepare to complete this assessment, you may want to think about other related issues to deepen your understanding or broaden your viewpoint. You are encouraged to consider the questions below and discuss them with a fellow learner, a work associate, an interested friend, or a member of your professional community. Note that these questions are for your own development and exploration and do not need to be completed or submitted as part of your assessment.

Various Forms of thet-Test

  • In what research situations should the paired samples t-test be used rather than the independent samples t-test?

Two Versions of the Independent Samplest-Test

  • Why are there are two different versions of the t-test on the SPSS printout and how you decide which one is more appropriate?

Application oft-Tests

  • Is there a research question from your professional life or career specialization that can be addressed by an independent samples t-test?
  • Why would a t-test be the appropriate analysis for this research question?
  • What are the variables and their scale of measurement?
  • What is the expected outcome? (For example, “The group 1 mean score will be significantly greater than the group 2 mean score because…”).

Required Resources

The following resources are required to complete the assessment.

In addition, you will need the grades.savfile that you created from the grades2.datfile in Assessment 1.

SPSS Software

The following statistical analysis software is required to complete your assessments in this course:

  • IBM SPSS Statistics (recent version for PC or Mac).

This course requires the following as a minimum:

  • IBM SPSS Statistics Standard GradPack. (The Base GradPack is not acceptable for use in this course.)

Versioning:This software is routinely updated. While it is recommended that you use the latest version of the software, you may use an older version if you already own it or have access to it, but it mustbe version 22 or higher. Be sure to use the version that is compatible with your operating system (PC or Mac).

Suggested Resources

The resources provided here are optional. You may use other resources of your choice to prepare for this assessment; however, you will need to ensure that they are appropriate, credible, and valid. The XX-FP7864 – Quantitative Design and Analysis Library Guidecan help direct your research, and the Supplemental Resources and Research Resources, both linked from the left navigation menu in your courseroom, provide additional resources to help support you.

Resources
Internet Resources
Resources
  • George, D., & Mallery, P. (2016). IBM SPSS statistics 23 step by step: A simple guide and reference (14th ed.). New York, NY: Routledge.
    • Chapter 11, “The t Test Procedure.”
  • Field, A. (2013). Discovering statistics using IBM SPSS (4th ed.). Thousand Oaks, CA: Sage.
  • Warner, R. M. (2013). Applied statistics: From bivariate through multivariate techniques (2nd ed.). Thousand Oaks, CA: Sage.
    • Chapter 5, “Comparing Group Means Using the Independent Samples t Test.”.
  • American Psychological Association. (2010). Publication manual of the American Psychological Association (6th ed.). Washington, DC: Author.

Read the Assessment 3 Context document (linked in the Resources, under the Required Resources heading) to learn about the concepts used in this assessment.

You will use the following resources for this assessment. They are linked in the Resources, under the Required Resources heading.

  • 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.savdata set:

  • gender.
  • gpa.
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:
    • t.
    • Degrees of freedom.
    • tvalue.
    • pvalue.
    • 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.

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