Independent t-test Lab Sheet SP2022

Independent t -Test Lab Data files are available on Canvas Effect size calculator can be found at https://lbecker.uccs.edu/ Open the data file Independent t-Test Exercise File 1 1. Complete the following: Bernice wishes to test the hypothesis that overweight individuals tend to eat faster than normal weight individuals. To test this hypothesis, she has two assistants sit in a McDonald’s restaurant and identify individuals who order the Big Mac Special (Big Mac, large fries, and large Coke) for lunch. The Big Mackers, as they are affectionately called by the assistants, are classified as overweight or normal-weight. The assistants identify 10 overweight and 30 normal-weight Big Mackers. The assistants record the amount of time it takes for the individuals to complete their meals. The SPSS data file contains a grouping variable with two levels, (overweight =1, normal-weight = 2) and time in seconds to eat the meal.  Compute an independent-samples t -test on these data. Report the t -values and the p -values assuming equal population variances and not assuming equal population variances below ( a and b )  Using the output, identify the following: mean eating time for overweight individuals, standard deviation for normal weight individuals, and results for the test of homogeneity of variances ( c through e )  Based on Levene’s test, which version of the t -test should we use? Enter your answer below.  Using the effect size calculator, calculate the Cohen’s d and report it below  In the space below, write a Results section based on your analyses What are the t -values and p -values for: a. assuming equal population variances b. not assuming equal population variances a. t (38) = -3.98, p < .001 b. t (31) = -5.40, p < .001 From the output, identify the following: c. Mean eating time for overweight individuals d. Standard deviation for normal weight individuals e. Results for the test of homogeneity of variances c. M = 589 d. SD = 82.95 e. F (1, 38) = 2.75, p = .11 Based on the results of Levene’s test, which version of the t -test should we use? Levene’s Test is not significant, so equal variances are assumed. Report the effect size in APA style. What is the magnitude of the effect size? Cohen’s d = -1.45. This is a large effect size. Write a Results section in APA style: An independent-samples t -test was

conducted to evaluate the hypothesis that overweight individuals tend to eat faster than normal weight individuals. The test was statistically significant, t (38) = -3.98, p < . 001, 95% CI [-165.12, -53.69]. Homogeneity of variances were assumed, F (1, 38) = 2.75, p = .11, p = .11. These results were counter to the research hypothesis. On average, overweight individuals ( M = 589, SD = 42.62) eat faster than those with normal weight ( M = 689.40, SD = 82.95). The Cohen’s d was -1.45. This is a large effect size. Paste all SPSS output tables for which values are reported or used to draw conclusions. Open the data file Independent t-Test Exercise File 2 2. Franco believes that teachers are more likely to have a positive view of inclusion in education if they have the experience of teaching both regular education and special education students in the classrooms (i.e., inclusive classrooms. He gained the cooperation of 40 seventh-grade teachers who have taught in similar junior high schools to participate in his study. To be included in the study, all teachers had to have graduated from college in the previous five years. Of these teachers, 25 teach in inclusive classrooms, and 15 teach in noninclusive classrooms. All teachers complete two versions of the Attitude Toward Inclusion Scale (ATIS). For one version (ATIS_SY), they respond to items as they would have completed it in their senior year of college. In the second version (ATIS_CB), they respond to the same items, but based on their current beliefs. The SPSS data file contains 40 cases and three variables: a factor called inclusion with two levels (teachers

were supportive to the hypothesis. On average teachers attitude towards noninclusive classrooms ( M = -0.20, SD = 11.71) was less than teachers attitude toward inclusive classrooms ( M = -19.28, SD = 20.89). The Cohen’s d was 1.06. This is a large effect size. Paste all SPSS output tables for which values are reported or used to draw conclusions.