PSYC 331 – Statistics for Psychologists
To be submitted by 5pm on Wednesday, 20 November 2019.
Answer all questions
Assignment must be typed and printed. Indicate your student ID number on front page. Use font size 12 and 1.5 lines spacing (Times New roman font).
1. Your company wants to improve sales. Past sales data indicate that the average sale was ¢100 per transaction. After training your sales team, recent sales data (taken from a sample of 25 salespersons) indicates an average sale of ¢130, with a standard deviation of ¢15. Did the training work? (Do not show full working steps)
2. A study was conducted to test the effect of self-imagery on social anxiety. Participants in the study rehearsed a negative self-image or a positive self-image prior to giving a speech. The researchers found that the negative image group felt more anxious than the positive image group. Assuming social anxiety was measured on an interval scale and that the scores were normally distributed, what statistical test would be most appropriate for testing the research hypothesis? Explain your answer.
3. A psychologist theorized that people could hear better when they have just eaten a large meal. Six individuals were randomly assigned to eat either a large meal or a small meal. After eating the meal, their hearing was tested. Assuming hearing ability was measured on an interval scale and that the scores were normally distributed, what test would be most appropriate for testing the research hypothesis? Explain your answer.
4. A study of the effects of color on reducing anxiety compared anxiety test scores of participants who completed the test printed on either soft yellow paper or on harsh green paper. The scores for five participants who completed the test printed on the yellow paper were 17, 19, 28, 21, and 18. The scores for four participants who completed the test on the green paper were 20, 26, 17, and 24. Using the .05 level, one-tailed (predicting lower anxiety scores for the yellow paper), what should the researcher conclude? (Do not show full working steps)
5. A group of researchers surveyed 58 people when they first started using Facebook (the researchers called this “Time 1”) and again 3 months later (referred to as “Time 2” by the researchers). At both time points, the participants completed a measure of social integration (a sense of belonging to a group of friends). Assuming the measure of social integration was on an interval scale, what statistical test would the researchers use in testing their research hypothesis? Explain your answer.
6. A program to decrease littering was carried out in the University of Ghana starting in August 2018. The amount of litter in the streets (average kilograms of litter collected per block per day) was measured during July before the program started and then the next July, after the program had been in effect for a year. What statistical test would be most appropriate for testing whether the amount of littering reduced? Explain your answer.
7. To determine whether caffeine consumption affects the ability to solve math problems, a researcher had one group solve math problems after taking a cup of caffeinated drink and another group solve math problems after taking a cup of water. The group who took the caffeinated drink completed 35 problems in one hour and the group that had water completed 20 problems in one hour. Assuming the number of problems solved is normally distributed in each group, what statistical test would be used to test the research hypothesis? Explain your answer.
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