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  1. Bias is present in the following observational studies. Homework Help ✎

    1. Explain why the question in the following scenario is biased:

      A political pollster seeking information on public attitudes toward funding of pornographic art by the National Endowment for the Arts (NEA) asks a simple random sample of 2000 U.S. adults, “Instead of supporting government censorship of artistic expression, are you in favor of continuing federal funding for artists whose work may be controversial?” Eight-five percent of those surveyed answered “yes.”

    2. Explain why the sample in the following scenario is biased:

      A flour company in Minneapolis wants to know what percentage of local households bake at least twice a week. A company representative calls 500 households during the daytime and finds that 50% of them bake at least twice a week.

    3. Identify a possible lurking variable in the following scenario:

      Dentists would like to determine if eating an apple a day keeps cavities away. Fifty patients who say they routinely eat an apple a day, and 50 patients who say they eat less than one apple a week, will have their dental records checked. The dentists will compare the number of cavities in the two groups.

People at home during the day are more likely to have time to bake than the general population.