The Pew Research Centers Report entitled "How Americans value public libraries in their communities," released December 11, 2013, asked a random sample of 6224 Americans aged 16 and over, "Have you used a Public Library website in the last 12 months?" In the entire sample, 30% said "yes." But only 17% of those in the sample over 65 years of age said "yes." Which of these two sample percents will be more accurate as an estimate of the truth about the population?
A. The result for those over 65 is more accurate
because it is easier to estimate a proportion for a small
group of people.
B. Both are equally accurate because both come
from the same sample.
C. The result for the entire sample is more accurate
because it comes from a larger sample.
An experiment that claimed to show that meditation reduces anxiety proceeded as follows. The experimenter interviewed the subjects and rated their level of anxiety. Then the subjects were randomly assigned to two groups. The experimenter taught one group how to meditate and they meditated daily for a month. The other group was simply told to relax more.
At the end of the month, the experimenter interviewed all the subjects again and rated their anxiety level. The meditation group now had less anxiety.
Psychologists said that the results were suspect because the ratings were not blind.
Step 1:
Explain what the results were suspect because the ratings were not blind means.
A. It means that the experimenter knew which subjects were taught to meditate.
B. It means that the subjects could see the experimenter.
C. It means that the subjects were allowed to choose between meditation or relaxation.
D. It means that the subjects were not randomly assigned to the groups.
Step 2:
Explain how lack of blindness could bias the reported results.
A. There were not enough subjects, who meditated daily.
B. The experimenter may have some expectation about whether or not meditation will lower anxiety; this could unconsciously influence the end-of-month assessment.
C. Subjects who were told to relax more, may have reported a high level of anxiety, because of their belief that relaxing more reduces anxiety.
D. Subjects who meditated daily, may have reported a low level of anxiety, because meditation really reduces anxiety.
