A survey was conducted by randomly selecting 20 American children and 20 British children to determine if there is a statistical difference in amount of time, they watch TV. Based on this example answer the following questions:
1. Why is a two samples t test most appropriate technique for this research example? 2. State (in words) the null and the alternate hypothesis. 3. Use the data set provided and conduct a two samples t test using SPSS. Use the SPSS command/actions listed below to conduct the analysis: Hint: Once you are in the Independent-Samples t Test dialog box in SPSS, you will have to Define your groups. 1. Click on Define Groups 2. In the area next to Group 1: type 1, and in the next to Group 2: type 2
3.Click on Continue number of minutes of TV watched by the British children?
5. What is the mean t statistic?
6. In the Equal Variances Assumed row, what is the t statistic?
7. What is the p value or significance?
8. Discuss the findings in regard to the Null and alternate
hypothesis using Morgan et al. (2002) pp. 10-12.
9. Why might these results be inaccurate due to the technique of Random Sampling (see Creswell, 2008)? Calculate the Effect size (Cohen’s d) for the paired samples t test output: (5 points). Use the following equation: d = M1
– M2/σD (Mean of Post-total Social Competency –Mean of Pre-total Social Competency)/Paired Differences Std. Deviation Cohen (1988) defined effect sizes as “small, d = .2,” “medium, d = .5,” and “large, d = 8”, stating that “there is a certain risk in inherent in offering conventional operational
definitions for those terms for use in power analysis in as diverse a field of inquiry as behavioral science” (p. 25). Discuss the meaning of the findings (1-2 sentences).Paired Samples Statistics 104.874531.1714.647113.874535.0625.227
SSBS Pre- total Social Competency S SBS Post- total Social. Competency pair 1 Mean NS td. Deviation Std . Error Mean Paired Samples Test-900018 .6952. 787-14 .617-3.383-3. 22944. 002
SSBS Pre-Total Social Competency-SSBS Post- total Social Competency Pair 1 Mean Std .Deviation Std .Error Mean Lower Upper 95% Confidence Interval of the Difference Paired Differences td f Sig.(2-tailed)
Cohen, J. (1988). Statistical power analysis for the behavioral sciences
(2nd ed.). Hillsdale, NJ: Lawrence Earlbaum Associates. Total Points Earned:
Assignment 4 Data I one-sample t Test.sav
Assignment 4 two-sample t Test (1).sav
Download PPT7 t-tests.ppt (3.02 MB)
