Psychology 2500: Data Analysis in Psychology
Name: _____________________________________________________
For questions 1, 2, and 3: Think well before you answer the questions. They are tricky!
1) Susan suspected that her pet hamster was chubbier than her roommate’s hamster. She weighed both critters once and found out that her hamster weighed 250 g, whereas her roommate’s hamster weighed 160 g. Can she conclude that her hamster is heavier than her roommate’s hamster? Why?
2) George suspected that cats in New Orleans were heavier than cats in Slidell. He went out, selected 10 cats at random in New Orleans and 10 cats at random in Slidell, and weighed them. He found that the cats in New Orleans weighed on average 10 lb (SD = 2.1 lb), whereas the cats in Slidell weighed 8 lb (SD = 1.8 lb). Can he conclude that cats in New Orleans differ from cats in Slidell in terms of body weight? Why?
3) Jennifer suspected that her dog ate more than the average dog (of the same breed) did. While the average dog eats 900 g of food a day (SD = 450), she monitored her dog daily for a month and found that her dog ate 1,100 g of food a day (SD = 530). Can she conclude that her dog eats more than the average dog? Why?
4) Fred thought that taking lots of vitamin C would help prevent aging. He successfully recruited 2,000 healthy participants for his study. Half of the participants received vitamin C, whereas the other half received a placebo for ten years. At the end of the study, he used a reliable measure of aging. He used a t test for independent samples and found a significant difference between the two groups. The p value was 0.01 and the effect size was 0.004. What can he conclude?
5) Emma wants to know the average body weight of pelicans in the New Orleans area. She cannot weight all pelicans, so the takes a random sample of 41 birds. She finds a mean of 3.5 kg with a standard deviation of 0.5 kg. In what body weight range can she be 95% confident that all pelicans in the New Orleans area will be?
