Interpreting skewness and kurtosis in spss

Histograms And Descriptive Statistics

1. Apply the appropriate SPSS procedures for creating histograms to generate relevant output.

2. Generate SPSS output of histograms and interpret them.

3. Generate SPSS output of descriptive statistics and interpret them.

Unit 3 - Descriptive Statistics: Application INTRODUCTION

Your first SPSS data assignment uses the SPSS grades.sav data file created in Unit 2. You will conduct a visual inspection of histograms. You will also analyze and interpret important measures of central tendency and dispersion.

OBJECTIVES

To successfully complete this learning unit, you will be expected to:

Unit 3 Study 1- Readings Use your IBM SPSS Statistics Step by Step text to complete the following:

• Review "An Introduction to the Example" in Chapter 1. This section provides definitions of SPSS variables used in your Unit 3 assignment.

• Read Chapter 6, "Frequencies." This reading addresses the following topics: ◦ Frequencies. ◦ Bar charts. ◦ Histograms. ◦ Percentiles.

• Read Chapter 7, "Descriptive Statistics." This reading addresses the following topics: ◦ Statistical significance. ◦ The normal distribution. ◦ Mean, median, and mode. ◦ Variance and standard deviation, skewness, and kurtosis. ◦ Maximum, minimum, range, and sum. ◦ Standard error.

Your SPSS Data Set

The grades.sav file is a sample SPSS data set. The fictional data represent a teacher's recording of student demographics and performance on quizzes and a final exam across three sections of the course. Each section consists of 35 students ( N = 105).

There are 21 variables in grades.sav. This week, complete the following:

• Open your grades.sav file and go to the Variable View tab.

[u03a1] Unit 3 Assignment 1 

Histograms and Descriptive Statistics Your first IBM SPPS assignment includes two sections in which you will:

1. Create two histograms and provide interpretations.

2. Calculate measures of central tendency and dispersion and provide interpretations.

Key Details and Instructions

• Submit your assignment as a Word document. • Begin your assignment by creating a properly formatted APA title page. Include a reference list at the

end of the document if necessary. On page 2, begin Section 1. • Write your report in narrative format, integrating your SPSS output charts and tables with your

responses to the specific requirements listed for this assignment. (See the Copy/Export Output Instructions in the Resources area.)

• Label all tables and graphs in a manner consistent with APA style and formatting guidelines. Citations, if needed, should be included in the text as well as in a reference section at the end of the report.

• Refer to the IBM SPSS Step-By-Step Guide: Histograms and Descriptive Statistics (in the Resources area) for additional help in completing this assignment.

Section 1: Histograms and Visual Interpretation

Section 1 will include one histogram of total scores for all the males in the data set, and one histogram of total scores for all the females in the data set.

Using the total and gender variables in your grades.sav data set, create two histograms:

• A histogram for male students. • A histogram for female students.

Copy the histogram output from SPSS and paste it into a Word document. Below the histograms in your Word document, provide an interpretation based on your visual inspection. Correctly use all of the following terms in your discussion:

• Skew. • Kurtosis. • Outlier. • Symmetry. • Modality.

Comment on any differences between males and females regarding their total scores. Analyze the strengths and limitations of visually interpreting histograms.

Section 2: Calculate and Interpret Measures of Central Tendency and Dispersion

Using the grades.sav file, compute descriptive statistics, including mean, standard deviation, skewness, and kurtosis for the following variables:

• id • gender • ethnicity • gpa • quiz3 • total

Copy the descriptives output from SPSS and paste it into your Word document. Below the descriptives output table in your Word document:

• Indicate which variables are meaningless to interpret in terms of mean, standard deviation, skewness, and kurtosis. Justify your decision.

• Next, indicate which variables are meaningful to interpret. Justify your decision. • For the meaningful variables, do the following:

◦ Specify any variables that are in the ideal range for both skewness and kurtosis. ◦ Specify any variables that are acceptable but not excellent. ◦ Specify any variables that are unacceptable. ◦ Explain your decisions.

• For all meaningful variables, report and interpret the descriptive statistics (mean, standard deviation, skewness, and kurtosis).

Submit both sections of your assignment as an attached Word document.

Resources

Histograms and Descriptive Statistics Scoring Guide.

• Includes all relevant output; no irrelevant output is included. No errors in SPSS output.

• Evaluates the concepts of skew, kurtosis, outliers, symmetry, and modality for two histograms.

• Analyzes the strengths and limitations of examining a distribution of scores with a histogram.

• Includes all relevant output; no irrelevant output is included. No errors in SPSS output.

• Evaluates meaningful versus meaningless variables reported in descriptive statistics.

• Evaluates descriptive statistics.

• Without exception, communicates in a manner that is scholarly, professional, and consistent with the expectations for members

in the identified field of study.

IBM SPSS Step-by-Step Guide: Histograms and Descriptive Statistics [DOC]. Copy/Export Output Instructions.