Question 1: In order to determine if smoking causes cancer, researchers surveyed a large sample of adults. For each adult they recorded whether the person had smoked regularly at any period in his or her life and whether the person had cancer. They then compared the proportion of cancer cases in those who had smoked regularly at some time in their life with the proportion of cases in those who had never smoked regularly at any point in their life. The researchers found there was a higher proportion of cancer cases among those who had smoked regularly than among those who had never smoked regularly. This is
an observational study.
an experiment, but not a double-blind experiment.
a double-blind experiment.
Question 2: Bob has a severe cold. His roommate takes a garlic tablet every morning and has not had a cold in two years. Bob's aunt also has a friend who takes garlic tablets daily and has not had a cold in over a year. Based on these data, Bob decides to start taking garlic tablets as soon as his cold clears up. Bob's decision is based on
anecdotal evidence.
an observational study based on available data.
an observational study based on a sample survey.
an experiment.
Question 3: A study of human development showed two types of movies to groups of children. Crackers were available in a bowl, and the investigators compared the number of crackers eaten by children watching the different kinds of movies. One kind of movie was shown at 8 A.M. (right after the children had breakfast) and another at 11 A.M. (right before the children had lunch). It was found that during the movie shown at 11 A.M., more crackers were eaten than during the movie shown at 8 A.M. The investigators concluded that the different types of movies had an effect on appetite. The results cannot be trusted because
the study was not double-blind. Neither the investigators nor the children should have been aware of which movie was being shown.
the investigators were biased. They knew beforehand what they hoped the study would show.
the investigators should have used several bowls, with crackers randomly placed in each.
the time the movie was shown is a lurking variable.
Question 4: Two variables in a study are said to be confounded if
one cannot separate their effects on a response variable.
they are highly correlated.
they do not have a normal distribution.
one of them is a placebo.
Question 5: A market research company wishes to find out whether the population of students at a university prefers brand A or brand B of instant coffee. A random sample of students is selected, and each one is asked to try first brand A and then brand B, or vice versa (with the order determined at random). They then indicate which brand they prefer. The response variable is
whether brand A or B is tried first.
which brand they prefer.
the two brands of coffee.
the identity of the student.
Question 6: Researchers wish to determine if a new experimental medication will reduce the symptoms of allergy sufferers without the side effect of drowsiness. To investigate this question, the researchers give the new medication to 50 adult volunteers who suffer from allergies. 44 of these volunteers report a significant reduction in their allergy symptoms without any drowsiness. This study could be improved by
including people who do not suffer from allergies in the study in order to represent a more diverse population.
repeating the study with only the 44 volunteers who reported a significant reduction in their allergy symptoms without any drowsiness, and giving them a higher dosage this time.
using a control group.
all of the above.
Question 7: One hundred volunteers who suffer from severe depression are available for a study. Fifty are selected at random and are given a new drug thought to be particularly effective in treating severe depression. The other 50 are given an existing drug for treating severe depression. A psychiatrist evaluates the symptoms of all volunteers after four weeks in order to determine if there has been substantial improvement in the severity of the depression. Suppose volunteers were first divided into men and women, and then half of the men were randomly assigned to the new drug and half of the women were assigned to the new drug. The remaining volunteers received the other drug. This would be an example of
replication.
confounding. The effects of gender will be mixed up with the effects of the drugs.
a block design.
a matched pairs design.
Question 8: In an experiment, an observed effect so large that it would rarely occur by chance is called
an outlier.
infuential.
statistically significant.
bias.
Question 9: A public opinion poll in Ohio wants to determine whether registered voters in the state approve of a measure to ban smoking in all public areas. They select a simple random sample of 50 registered voters from each county in the state and ask whether they approve or disapprove of the measure. This is an example of
a systematic county sample.
a stratified sample.
a multistage sample.
a simple random sample.
Question 10: Simple random sampling
reduces bias resulting from poorly worded questions.
offsets bias resulting from undercoverage and nonresponse.
reduces bias resulting from the behavior of the interviewer.
none of the above.
Question 11: A news release for a diet products company reports: "There's good news for the 65 million Americans currently on a diet." Its study showed that people who lose weight can keep it off. The sample was 20 graduates of the company's program who endorse it in commercials. The results of the sample are probably
biased, overstating the effectiveness of the diet.
biased, understating the effectiveness of the diet.
unbiased since these are nationally recognized individuals.
unbiased but they could be more accurate. A larger sample size should be used.
Question 12: A television station is interested in predicting whether voters are in favor of an increase in the state sales tax. It asks its viewers to phone in and indicate whether they support or are opposed to an increase in the state sales tax in order to generate additional revenue for education. Of the 2633 viewers who phoned in, 1474 (55.98%) were opposed to the increase. The number 55.98% is
a statistic.
a parameter.
a sample.
a population.
Question 13: A television station is interested in predicting whether voters are in favor of an increase in the state sales tax. It asks its viewers to phone in and indicate whether they support or are opposed to an increase in the state sales tax in order to generate additional revenue for education. Of the 2633 viewers who phoned in, 1474 (55.98%) were opposed to the increase. The population of interest is
all people who will vote on the sales tax increase on the day of the vote.
all regular viewers of the television station who own a phone and have participated in similar phone surveys in the past.
the 2633 viewers who phoned in.
the 1474 viewers who were opposed to the increase.
Question 14: An opinion poll uses random digit dialing equipment to dial 2000 randomly chosen residential telephone numbers. Of these, 621are unlisted numbers. This isn't surprising, because 35% of all residential numbers are unlisted.
State whether number 621 is a parameter or a statistic. State whether number 35% is a parameter or a statistic.