Question

ssignment #5 12. Measures of effect size for the repeated-measures t A Aa Previous studies have shown that playing video games can increase visual perception abilities on tasks presented in the gaming zone of the screen (within 5 degrees of the center). A graduate student is Interested in whether playing video games increases peripheral visual perception abilities or decrsases attantion to peripheral regions because of foaus on the gaming zone. For her study, she selects a random sample of 64 adults. The subjects complete a difficult spatial percaption task to detarmine baseline levels of their abilities. After playing an action video game (a first-person combat simulation) for 1 hour a day over 10 days, they complete the dificult parception task for a second time. Before playing the action video game, the mean score in their accuracy on the spatial task was 0.42. After playing the action video game, the mean score was 0.8 lower. The graduate student has no presupposed assumptions about whether playing video games increases peripheral visual perception abilities or decreases attention to peripheral regions because of focus on the gaming zone, so she formulates the null and alternative hypotheses as: Ho: Po -0 Hi: po 0 Assume that the data satisfy all of the required assumptions for a repeated-measures t test. The graduate student calculates the following statistics for her hypothesis test: -0.8 Mean difference (Mo) Estimated population standard deviation of the differences (s) 2.4 0.3000 Estimated standard error of the mean differences (suo) 63 Degrees of freedom (df) -2.67 The t statistic The critical values of t when a.05 *1.998 Notice that since the t statistic (-2.67) is in the critical region (t<-1.998 or t> 1.998), the hypothesis test is significant when a- 05. A 95% confidence interval for the mean difference is -0.59940 s oS 0.59940 -6.289 s uo S 1.060 -1.399s oS 1.060 -1.399 sos-0.201 Using Cohen's Use Cohen'sd to calculate the effect size. The absolu effect size. criteria, this is a % of the Use r to calculate the effect size. The is vanability in the peripherel visual perception is explained by whether it was measured before or after playing the action video game. (Round to the nearest percent.) This value of r means that, on average,

Answer 1

Formula for the confidence interval of paired data in the light of paired sample t-test :- Mean differecne + talon-1*- estimated standard deviation of differences Vn n = number of data points. = 64 So ee, Mo-ta/2, n-1 V sup<Motta/20-1x . Mo-to/2,n-1 x - -0.8 - 1.998x204 2.4 - - - 1 .3gg. in V2 V64 and not tala, noix s in =-0.8t 1.998 X 2.4 N64 = -0.2006 -0.201 :. The confidence intervalis:- - 1.1399 SUD -0.201