0.5 Writing up parametric independent samples t test

Writing up your parametric independent samples t

About the Authors

• John R. Slate is a Professor at Sam Houston State University where he teaches Basic and Advanced Statistics courses, as well as professional writing, to doctoral students in Educational Leadership and Counseling. His research interests lie in the use of educational databases, both state and national, to reform school practices. To date, he has chaired and/or served over 100 doctoral student dissertation committees. Recently, Dr. Slate created a website, Writing and Statistical Help to assist students and faculty with both statistical assistance and in editing/writing their dissertations/theses and manuscripts.
• Ana Rojas-LeBouef is a Literacy Specialist at the Reading Center at Sam Houston State University where she teaches developmental reading courses. She recently completed her doctoral degree in Reading, where she conducted a 16-year analysis of Texas statewide data regarding the achievement gap. Her research interests lie in examining the inequities in achievement among ethnic groups. Dr. Rojas-LeBouef also assists students and faculty in their writing and statistical needs on the Writing and Statistical website, Writing and Statistical Help

The following is an example of how to write up (in manuscript text) your Parametric Independent Samples t test statistics. This module is used with a larger Collection (Book) authored by John R. Slate and Ana Rojas-LeBouef from Sam Houston State University and available at: Calculating Basic Statistical Procedures in SPSS: A Self-Help and Practical Guide to Preparing Theses, Dissertations, and Manuscripts

Elementary School Beginning Teacher Percentages and Teacher Salary: Accountability Rating Differences

Research questions

In this study, the following research questions were addressed:

1. What is the difference in beginning teacher percentages between Exemplary elementary schools and Academically Unacceptable elementary schools?; and
2. What is the difference in beginning teacher salary between Exemplary elementary schools and Academically Unacceptable elementary schools?

Results

The average percent of beginning teachers employed at Texas Exemplary elementary schools was 5.26%, compared to an average of 11.94% beginning teachers employed at Texas Academically Unacceptable elementary schools. Concerning the average teacher salary of beginning teachers, the mean salary was $40,080.06 for beginning teachers at Exemplary elementary schools whereas the mean salary was $38,414.98 for beginning teachers at Academically Unacceptable elementary schools. Readers are referred to Table 1 for the descriptive statistics concerning these variables.

Prior to conducting inferential statistics to determine whether differences were present between Exemplary and Academically Unacceptable elementary schools in their beginning teacher percentages and beginning teacher salaries, checks were conducted to determine the extent to which the data were normally distributed. Of the standardized skewness coefficients (i.e., the skewness value divided by its standard error) and the standardized kurtosis coefficients (i.e., the kurtosis value divided by its standard error), all were within the limits of normality, +/-3 (Onwuegbuzie&Daniel, 2002). Accordingly, parametric independent samples t -tests were conducted to answer the two research questions.

The independent samples t -test revealed a statistically significant difference between Exemplary elementary schools and Academically Unacceptable elementary schools in their percent of beginning teachers, t (49.46) = -4.58, p <.001. This difference represented a large effect size (Cohen’s d ) of 0.83 (Cohen, 1988). Academically Unacceptable elementary schools had a statistically significantly higher percentage of beginning teachers, more than twice as high, than did Exemplary elementary schools.

Regarding beginning teacher salary, the independent samples t -test revealed a statistically significant difference between Exemplary elementary schools and Academically Unacceptable elementary schools, t (50.47) = 2.11, p = .04. This difference represented a small effect size (Cohen’s d ) of 0.31 (Cohen, 1988). Exemplary elementary schools had a statistically significantly higher teacher salary for beginning teachers, $1,665.08 higher, than the beginning teacher salary at Academically Unacceptable elementary schools.

References

• Cohen, J. (1988). Statistical power analysis for the behavioral sciences (2nd ed.) . Hillsdale, NJ: Lawrence Erlbaum.
• Onwuegbuzie, A. J.,&Daniel, L. G. (2002). Uses and misuses of the correlation coefficient. Research in the Schools, 9 (1) , 73-90.

Spss statistical output

Figure 1. statistics

Figure 2. independent samples test for percent of beginning teachers

Figure 3. independent samples test for beginning teacher salary