Are mosquitoes attracted differently to beer drinkers than to water drinkers? In

Question

Are mosquitoes attracted differently to beer drinkers than to water drinkers? In a study using 43 college age volunteers, each subject was randomly assigned either to drink 350 ml of beer (5.5% alcohol) or the same amount of water. Researchers then counted the number of mosquito bites they received while sitting for ten minutes in a screen tent containing hundreds of hungry mosquitoes. The summary statistics are below. Assume neither distribution of number of mosquito bites is strongly skewed.

1.     What is the response variable? Is it categorical or quantitative?

2.     What is the explanatory variable? Is it categorical or quantitative?

3.     Define the parameter of interest in words and notation. (Circle one)

A.      = the effect of drinking beer or water on the number of mosquito bites.

B.     = the difference in true proportion of people bitten by mosquitoes when drinking beer versus water.

C.      = the difference in mean number of mosquito bites after drinking beer versus after drinking water in this sample.

D.     the difference in true mean number of mosquito bites after drinking beer versus after drinking water.

4.     Before conducting the experiment, scientists did not know if beer would attract or repel mosquitoes. What is the alternative hypothesis? (Circle one.)

5.     Write the null hypothesis in words in the context of this problem.

6.     Check whether the validity conditions are met to use a theory-based approach to analyze these data.

Explanation / Answer

1)

the response variable is number of mosquito bites received so it is quantitative

2)

explanatory variable is a categorical variable . it takes 2 categories one is beer drinkers and other one is water drinkers. let's denote beer drinker by 0 and water drinker by 1.

3) answer will be A since it is stated in the question that experimenter wants to understand whether mosquitoes attracted differently to beer drinkers and water drinkers.

5)

H0: both beer drinkers and water drinkers attract mosquitoes equally

4)

H1: both beer drinkers and water drinkers attract mosquitoes differently

where H0 is null hypothesis and H1 is alternative hypothesis.

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