Social psychologists at the University of California at Berkeley wanted to study the effect that staring at drivers would have on driver behavior (Ellsworth, Carlsmith, and Henson, 1972). In a randomized experiment, the researchers either stared or did not stare at the drivers of automobiles stopped at a campus stop sign. The researchers timed how long it took each driver to proceed from the stop sign to a mark on the other side of the intersection. Suppose that the crossing times, in seconds, were as follows:

No-Stare Group Stare Group 8.3 5.6 5.5 5.0 6.0 5.7 8.1 6.3 8.8 6.5 7.5 5.8 7.8 4.5 7.1 6.1 5.7 4.8 6.5 4.9 4.7 4.5 6.9 7.2 5.2 5.8Histogram of Difference Probability Plot of Difference Normal - 95% CI Frequency Percent 0.2 14 2.6 Difference Difference WORKSHEET 1+ Paired T-Test and CI: No-Stare Group, Stare Group Descriptive Statistics Samples N. Mean StDev SE Meant No-Stare Group- 13 6.777 1.295 0.359: Stare Group. | 13 5.5921 0.822 0.228 - Estimation for Paired Difference 99% Lower Bound. ~ Mean StDey SE Mean for u difference 1.185 1.175 0.326 0.3116 _ difference: mean of (No-Stare Group - Stare Group)+ Test Null hypothesise How difference = 0se Alternative hypothesiss H,: u difference > ode T-Value P-Value 3.64 0.00216Histogram of Stare Group Histogram of No-Stare Group 20 Frequency Frequency LE No-Stare Group Stare Group Probability Plot of No-Stare Group Probability Plot of Stare Group Normal - 95% CI Normal - 93% CI Percent percent No-Stare Group Stare Group WORKSHEET 1 Two-Sample T-Test and Cl: No-Stare Group, Stare Group- Method Hi: mean of No-Stare Groupie Jz: mean of Stare Group Difference: M1 - Mat Equal variances are not assumed for this analysis. Descriptive Statisticse Sample - N Mean StDey SE Meanit No-Stare Group: 131 6.78 1.29 Stare Group 1 13 5.592 0.822 0.23/ Estimation for Differences 99% Lower Bound.~ Difference for Difference 1.185 0.109 Test Null hypothesis | Ho: 14 - H2 = Ode Alternative hypothesis { H1: 1 - Uz > Ofje] T-Value DF P-Value 2.781 201