Stat 1040
Chapter 19 Solutions

  1. Too high. Larger households are more likely to have someone home, so it's likely the sample is substituting larger households for smaller ones.

  2. No. The hallmark of a probability sample is the ability of the investigators to compute the chance that any particular individuals in the population will be selected for the sample. See page 354. In this sample, how can the investigator measure things such as the chance that a certain student will pass by at a certain time?

  3. The hospital with fewer live male births is more likely to have 55% or more male births. This question is much like numbers 4 and 6 from chapter 16. The SE as a percentage decreases as the number of draws increases, so the hospital with more live births will have a percentage of male births closer to the expected value of 52%, and a smaller chance of having a percentage above 55%.

    1. The survey isn't representative of all teenagers because only "high achievers" were surveyed.
    2. Probably not. Important questions we should ask: How were the 5,000 chosen? With only 1,957 completed, returned surveys what about non-response bias?