Exam 7: Chi-Square Tests for Categorical Variables

Use the following Observed counts from a sample are provided in the following table. The expected counts from a null hypothesis are given in parentheses. -What is the - test statistic?

Use the following to answer questions On November 15 - 18, 2012 Gallup conducted a survey of 1,015 randomly selected U.S. adults about "Black Friday" shopping. They asked the following question: "As you know, the Friday after Thanksgiving is one of the biggest shopping days of the year. Looking ahead, do you personally plan on shopping on the Friday after Thanksgiving, or not?" Their results, broken down by sex, are summarized in the provided two-way table. -Is it appropriate to use a chi-square test to test for an association between sex and plans to shop the Friday after Thanksgiving? Briefly explain.

Use the following Are all colors equally likely for Milk Chocolate M&M's? Data collected from a bag of Milk Chocolate M&M's are provided. -Is a chi-square test appropriate in this situation? Explain briefly.

Use the following M&M's, the popular candy-coated chocolate treats, come in a variety of flavors. Two popular varieties are Milk Chocolate (sometimes referred to as "Plain") and Peanut. Does the Mars Company (the maker of M&M's) use the same color distribution (frequency of colors) for all varieties, or does it depend on variety? Data were collected on the two varieties and computer output for a chi-square test of association is provided. Rows: Variety Columns: Color Pearson Chi-Square = 6.183, DF = 5, P-Value = 0.289 -Test, at the 5% level, if there is a significant association between variety and color. Include all details of the test.

Use the following Upon request, the Mars Company (the maker of M&M's) will provide the color distribution for their candies. As of August 2009, they noted that "Our color blends were selected by conducting consumer preference tests, which indicate the assortment of colors that pleased the greatest number of people and created the most attractive overall effect. On average, our mix of colors for M&M'S CHOCOLATE CANDIES is: M&M'S MILK CHOCOLATE: 24% cyan blue, 20% orange, 16% green, 14% bright yellow, 13% red, 13% brown." Data collected from a bag of Milk Chocolate M&M's are provided. We want to determine if this sample provides evidence that the color distribution has changed since August 2009. -Find the expected counts for each color using the sample size (420 total candies) and null hypothesis.

Use the following Are all colors equally likely for Milk Chocolate M&M's? Data collected from a bag of Milk Chocolate M&M's are provided. -Calculate the chi-square test statistic. Report your answer with three decimal places.

Use the following In a survey conducted by the Gallup organization September 6-9, 2012, 1,017 adults were asked "In general, how much trust and confidence do you have in the mass media - such as newspapers, TV, and radio - when it comes to reporting the news fully, accurately, and fairly?" The results are summarized in the provided table. We are interested in testing whether or not the four responses are equally likely. -Which opinion has the largest contribution to the chi-square test statistic? For this age group, is the observed count smaller or larger than the expected count?