PSYC 421 Week 2 SPSS Assignment Part 1 Example

SPSS Assignment Part 1: Describing the Demographic Characteristics of a Normative Sample With Tables, Graphs and a Summary

Purpose

A test score has meaning only in relation to something, and for norm-referenced tests that something is the performance of a normative sample. Cohen and Swerdlik (2018) explain that norms are only as useful as the match between the norm group and the people being tested. This report describes the demographic characteristics of the normative sample for the Campus Stress Inventory, a composite 40-item self-report measure of academic and personal stress, so that test users can judge for whom the norms are appropriate.

Method

The data file contained responses from 250 undergraduate students at four universities who completed the inventory during the fall semester. Five demographic variables were analyzed in SPSS. Gender, ethnicity and class standing are nominal variables, although class standing also has an order, so frequencies and percentages were computed for each. Age and weekly hours of paid employment are ratio variables, so the mean, standard deviation, median, minimum and maximum were computed, along with skewness to check whether the mean was a fair summary. Three participants left the employment question blank, so that variable is based on 247 cases; no other values were missing. Before running the analyses, each variable was given a descriptive label and each numeric code a value label, so that 1 for gender appears as Female in the output rather than as a bare number. The Frequencies procedure produced the counts and percentages, and the Descriptives and Explore procedures produced the continuous statistics, the skewness values and the histogram. Field (2018) recommends checking the shape of a distribution before choosing a summary statistic, and Explore makes that check easy by displaying the histogram, a boxplot and the skewness value together.

Results

Table 1 presents the descriptive statistics.

Figures

Figure 1, formatted as the American Psychological Association (2020) manual directs, is a histogram of age with a normal curve overlaid. It shows a strong right skew. Most participants were between 18 and 23, with a long tail of older students extending to 58. Because of that skew, the median of 22 describes the typical participant better than the mean of 24.6, which is pulled upward by the smaller group of students over 30.

Figure 2, a bar chart of class standing, shows four bars of nearly equal height, from 59 third-year students to 68 first-year students. A bar chart was chosen because class standing is categorical; a histogram would wrongly imply a continuous scale.

Descriptive Summary

The normative sample is a fairly balanced group of traditional-age undergraduates, spread evenly across the four years of study, with somewhat more women than men and a majority of White students. Just over half of the sample identified as female, and about two in five identified as male. Roughly half identified as White, with Black or African American and Hispanic or Latino students forming the next largest groups. The median age of 22 and the strong right skew indicate that most participants were in the usual college age range, though a meaningful minority were older students. Participants worked an average of about 14 hours a week, with a nearly symmetric spread from no paid work to full-time employment. In practical terms, the typical member of the norm group is a 22-year-old student with a part-time job, and a test user comparing a new respondent with these norms is comparing that person with students much like this.

Implications for Test Use

These characteristics suggest that the Campus Stress Inventory norms are most appropriate for undergraduates at four-year institutions between about 18 and 25. Cohen and Swerdlik (2018) caution that norms may not generalize to groups that are poorly represented in the normative sample. Because only a small share of participants were over 30, comparisons for older adult learners, such as many online students, should be made cautiously, and the same caution applies to Asian students and to students who did not report a gender, whose small numbers limit the stability of any subgroup norms. Users should also note that all participants attended four universities in one semester, so stress levels may reflect that term's circumstances. Part 2 of the assignment will examine whether the inventory's scores are reliable and valid in this sample.

References

American Psychological Association. (2020). Publication manual of the American Psychological Association (7th ed.). https://doi.org/10.1037/0000165-000

Cohen, R. J., & Swerdlik, M. E. (2018). Psychological testing and assessment: An introduction to tests and measurement (9th ed.). McGraw-Hill Education.

Field, A. (2018). Discovering statistics using IBM SPSS statistics (5th ed.). SAGE Publications.