Homework #3-Chapter8&9 (20pts for turned in on time) (24pts)Of the following stu

ID: 3069110 • Letter: H

Question

Homework #3-Chapter8&9 (20pts for turned in on time) (24pts)Of the following study, first identify what kind of study it is (observational study an experiment, what are SUBJECTS, FACTOR(S), and TREATMENTS? (a) (6pts)A researcher wants to see f multivitamin pills will reduce the chance of heart 7. experiment, then write down the explanatory variable and response variable. If it is attacks for people over 65 years old. He collaborated with some doctors in the network, and data are collected about 1,000 people indicating whether or not they take multivitamin pills, and whether or not they had a heart attack. (2) (6pts)As men age, their testosterone levels gradually decrease. This may cause a reduction of lean body mass, an increase in fat and other undesirable changes. A researcher wants to know if testosterone supplements reverses some of th effects. In the study, there were 237 participants with low testosterone level of similar age. Some of the participants were asked to take testosterone supplements daily for a month, while the rest were asked to take placebo pills daily for a month. None of the participants knew which pills they were asked to take. Their testosterone levels were tested again after a month. ese (3) (6pts)A psychologist wants to know if the difficulty of a task influences people estimate of how long they spend working on it. She designs two sets of puzzles (Puzzle A and Puzzle B) with different difficulty level that subjects can work through on computers. She has 30 students with similar age and physical condition to participate. Of the 30 students, she randomly selected 15 to work on the easy set, and the other 15 work on the difficult set. After 20 minutes, the researcher tells them to stop and asks them how much time they have spent.

Explanation / Answer

1) It is an observational study because the researcher only indicates the 1000 people whether or not taking multivitamin pills,whether or not had an heart attack.

Here whether or not had an heart attack depends on whether or not taking multivitamin pills, So,explanatory variable is whether or not taking multivitamin pills, Response variable is whether or not had an heart attack

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2)Here at first researcher measures the collected 237 people(of same age level) having low testosterone.Then some of them were asked to take testosterone supplement while rest were asked to take placebo pills. Testosterone level were again measured after 1 month.So, this is an experimental study because experimentor tests the level of testosterone and is doing an experiment on it.

Subjects-237 participant withlow testosterone (same age level)

Factor-level of testosterone.

treatment-testosterone supplement and placebo pills.

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3)Here researcher took 30 students of same age level and of same physical condition. And then these people were divided in two groups of 15 people and the groups were given two diffferent puzzles of different level of difficulties and to solve them in computer within 20 minutes.So the researcher is doing an experiment. hence it is an experimental study.

Subject-30 students of same age level and of same physical condition.

Factors-how they use 20minutes.

treatment-two different level of difficult puzzle.

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Here the researcher only visits 16 farmers and each farm ,he will collect data about type of grain used and wait agin of the cow.Hence researchere only observed the data.Hence it is an observational study.

Here wait gain of a cow depends on type of grain they are fed.

explanatory variable-type of grain the cow is fed

response variable-wait gain of a cow

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factor-colon cancer.

treatments-Daily Beta carotene,Daily Vitamin C &E,Daily All three Vitamins and Daily Placebo

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