For each of the prompts below, decide whether the parameter of interest is a mea
ID: 3357524 • Letter: F
Question
For each of the prompts below, decide whether the parameter of interest is a mean difference (matched-pairs, ) or a difference in means (independent samples, ).
a) Does it matter where you take your car to get body work done after being in an automobile accident? A random sample of ten cars that needed body work after an accident was obtained. For each car, an estimate for repairs in $ was obtained from two different body shops: Crash-Fix (a national chain) and Joe's-Garage (a local shop). Your goal is determining if, on the average, the estimate ($) for repairs from Crash-Fix is larger than what is found with Joe’s-Garage.
b) A study wants to determine how millennials best complete a task. A sample of 20 millennials was obtained such that each was randomly assigned to either be in one of two groups. One group worked in "noisy" conditions while the other group worked in "quiet" conditions. Each participant was given a task to complete where the amount of time (in hours) needed to complete the task was recorded.
c) Students in a large calculus class believe that their professor grades exams too hard with regard to not getting enough partial credit. In order to check this claim, the professor had a colleague also grade 10 exams. So these 10 exams had two grades, one from the professor and one from the colleague. The Professor's research question is: Does the data suggest that the colleague grades less harshly, on the average?
Explanation / Answer
(a) Parameter of interest is a mean difference (matched - pairs)
EXPLANATION: Here, the same sample: Sample of 10 cars that needed body work after an accident: estimate of repairs is compared between two shops.
(b) Parameter of interest is a difference in means (independent samples):
EXPLANATION: Here, two different samples: 20 millennaials assigned to two groups.
(c) Parameter of interest is a mean difference (matched - pairs):
EXPLANATION: Here, same sample: 10 exams, with two different grades.
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