7.1 Multiple Choice

At a particular college, 78% of all students are receiving some kind of financial aid. The school newspaper selects a random sample of 100 students and 72% of the respondents say they are receiving some sort of financial aid. Which of the following is true?

• 78% is a population and 72% is a sample.

• 72% is a population and 78% is a sample.

• 78% is a parameter and 72% is a statistic.

• 72% is a parameter and 78% is a statistic.

• 78% is a parameter and 100 is a statistic.

A statistic is an unbiased estimator of a parameter when

• the statistic is calculated from a random sample.

• in a single sample, the value of the statistic is equal to the value of the parameter.

• in many samples, the values of the statistic are very close to the value of the parameter.

• in many samples, the values of the statistic are centered at the value of the parameter.

• in many samples, the distribution of the statistic has a shape that is approximately Normal.

In a residential neighborhood, the median value of a house is $200,000. For which of the following sample sizes is the sample median most likely to be above $250,000?

• n=10

• n=50

• n=100

• n=1000

• Impossible to determine without more information.

Increasing the sample size of an opinion poll will reduce the

• bias of the estimates made from the data collected in the poll.

• variability of the estimates made from the data collected in the poll.

• effect of nonresponse on the poll.

• variability of opinions in the sample.

• variability of opinions in the population.