Does stress affect the recall ability of police witnesses? This issue was studied in an experiment that tested eyewitness memory a week after a nonstressful interrogation of a cooperative suspect and a stressful interrogation [the way of questioning] of an uncooperative suspect. The numbers of details recalled a week after the incident are summarized in the margin (based on data from "Eyewitness Memory of Police Trainees for Realistic Role Plays," by Yuille et al., Journal of Applied Psychology, Vol. 79, No. 6). Use 0.01 level of significance to test the claim in the article that stress decreased the amount recalled. Assume equal population variances. Nonstress Stress n, = 40 X= 53.3 S = 11.6 l, = 40 X = 45.3 S, = 13.2 a. Claim (in symbolic form): Ho: На: b. level of significance: test-statistic: tail of distribution:- c. Decision Rule: Reject Ho if d. Computation e. Decision (Reject Ho or Failed to reject Ho) f. Conclusion

A group of boys believe that there is a relationship between the act of sending flowers to a girl and texts received as a result. A study was carried out in which a sample of girls were asked whether they received any flowers and how many texts they sent in response. a)What type of variable is the explanatory variable? Quantitative Categorical   b) What type of variable is “number of texts sent in response?” Categorical Quantitative   c)What type of visual display should be used to summarize this data?   Bar chart Side-by-side boxplots Histogram Dot plot

We are interested in analysing the effect of the lockout laws introduced in some areas of the Sydney CBD and nearby surrounds on the number of alcohol-related violent incidents.  Suppose we have two samples of data on the number of violent incidents in a number of local areas of the Sydney CBD and nearby surrounds. Pubs, hotels and clubs located in a subset of these areas became subject to the lockout laws when they were introduced in 2014. The first sample is from 2010 before the introduction of the lockout laws, and the second is from 2015 after the introduction of the law. The hypothesis we wish to test is that the introduction of the lockout laws reduces violent incidents in the areas in which the lockout laws were put in place.  We use a difference-in-difference model on the pooled data from 2010 and 2015. We find the following results: viol_inc hat = 33.21 (5.29) + 12.43lockout (7.01) – 4.19Yr2015 (2.98) – 3.32 (lockout x Yr2015) (1.85) N = 181, R^2 = 0.128 Where: viol_incis the…

Researchers investigate how the presence of cell phones influence the quality of human interaction.  Subjects are randomly selected from a population and divided into an experimental group that is asked to leave their phones in the front of the room and a control group that are not asked to leave their cell phones at the front of the room.  Subjects are left alone for 10 minutes and then asked to take a survey designed to measure quality of interactions they had with others in the experiment.  What statistical test is appropriate?