STAT107 Ch 4 LC

In an effort to improve a statistics course, we want to interview randomly chosen students about their attitudes toward the class. Because there are 800 students currently enrolled, and six instructors who teach sections of the course, what type of sample will give the best information? Voluntary Response Sample Convenience Sample Simple Random Sample Stratified Sample

Stratified Sample

In a survey about a new immigration law in Georgia, "46% of the 132 Georgia farmers, agricultural processors, and farm service businesses who responded said they were experiencing some degree of labor shortage" (Al Hackle, "Groups seek reform, not repeal," Statesboro Herald, June 23, 2011). In interpreting the results of this survey, we should be wary of what type of bias? I. Nonresponse Bias II. Question Wording Bias III. Undercoverage Bias

I. only

_____ error can be present even in a census.

Nonsampling

Why might a poll not report the actual questions asked in a survey? The questions are worded in such a way as to influence a particular response This information is not necessary to evaluate the conclusions drawn by the researchers. As long as the sample size is large enough, the details of the questions asked are not important.

The questions are worded in such a way as to influence a particular response

Good sampling technique includes the art of reducing all sources of _____.

bias

Random sampling eliminates _____ in choosing a sample.

bias

An important characteristic of probability samples is that _____. results from any sample are usually not the same as results for the entire population. they will always allow all possible samples from the population. they give an equal chance to all the samples that are allowed. they are all random samples.

results from any sample are usually not the same as results for the entire population.

The Harris Poll organization has been existence since 1956, when it was founded by Louis Harris who famously was John Kennedy's pollster in 1960. Of late, they do much of their research through the Harris Poll Online panel, which polls people through the Internet. Even though the sample can be carefully balanced on the basis of certain demographics, such as gender and race, one caution in interpreting results is _____. people will probably treat the survey invitations as spam. that the wording of the questions may confuse people. Because the sample is balanced for all these factors, no cautions are necessary. there will be undercoverage bias because only people with Internet access will be able to participate.

there will be undercoverage bias because only people with Internet access will be able to participate.

When a polling company obtains a sample for their Internet survey, which leaves out whole groups of the population who do not use the Internet, this Internet poll suffers from _____. processing error random sampling error response errors undercoverage

undercoverage

Using a local telephone book to select a simple random sample could introduce which type of bias?

undercoverage bias

To adjust for nonsampling errors, once the data are collected, you can _____ the responses.

weight