1- A study of malaria transmission in Africa tested whether drinking beer increa
ID: 3061035 • Letter: 1
Question
1- A study of malaria transmission in Africa tested whether drinking beer increased attractiveness to mosquitoes. Yes, this is a real story (Lefevre et al. 2010. PLOS One5:e9546), and for simplicity I have changed some details from what they actually did. The researchers opened a container of 50 mosquitoes and looked at what proportion of the 50 mosquitoes left the container and flew towards the volunteer person. They did this experiment with 30 persons and each person was tested twice, once before they drank anything and then (an hour later) after they had consumed a beer. Assuming that the proportions of mosquitoes are normally distributed and the variances are similar, what would be the best test to see if more mosquitoes are attracted to people after drinking a beer?
A
compare the two independent confidence intervals
B
a paired t-test comparing each person's number of mosquitos before and after the beer
C
an independent two sample t-test comparing the number of mosquitos in the before and after beer groups
D
a chi-square contingency test of the number of mosquitoes before and after for each person
2-Which of the following examples is not a test with dependent samples.
A
Comparing mean life satisfaction scores for seniors (age 65+) and for middle-aged adults (ages 40-50).
B
Comparing pre- and post-test number of hours of sleep daily.
C
Comparing number of alcoholic drinks consumed in a typical day for pairs of twins.
D
Comparing the number of words read per minute for students before and after a class in speed reading.
Explanation / Answer
ANSWERS:
1) (B)
a paired t-test comparing each person's number of mosquitos before and after the beer
EXPLANATION: A paired t test is used to find the significance difference in means of before and after the intervention
2) (A)
Comparing mean life satisfaction scores for seniors (age 65+) and for middle-aged adults (ages 40-50).
EXPLANATION: Here the groups are different. Therefore it is not related dependent samples
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