What is the population of interest in this study?

Exam 1 Econ 261

1.

A Bloomberg Businessweek North American subscriber study collected data from a sample of 2861 subscribers. Fifty-nine percent of the respondents indicated an annual income of $75,000 or more and 50% reported having an American Express credit card.

a. What is the population of interest in this study?

b. Is annual income a categorical or quantitative variable?

c. Is ownership of an American Express card a categorical or quantitative variable?

d. Does this study involve cross-sectional or time series data?

e. Describe any statistical inferences Bloomberg Businessweek might make based on the survey.

2.

A seven-year medical research study reported that women whose mothers took the drug DES during pregnancy were twice as likely to develop tissue abnormalities that might lead to cancer as were women whose mothers did not take the drug.

a. This study compared two populations. What were the populations?

b. Do you suppose the data were obtained in a survey or an experiment?

c. For the population of women whose mothers took the drug DES during pregnancy, a sample of 3980 women showed that 63 developed tissue abnormalities that might lead to cancer. Provide a descriptive statistic that could be used to estimate the number of women out of 1000 in this population who have tissue abnormalities.

d. For the population of women whose mothers did not take the drug DES during pregnancy, what is the estimate of the number of women out of 1000 who would be expected to have tissue abnormalities?

e. Medical studies often use a relatively large sample (in this case, 3980). Why?

3.

The DATAfile MedianHousehold contains the median household income for a family with two earners for each of the fifty states (American Community Survey, 2013).

1. Construct a frequency and a percent frequency distribution of median household income. Begin the first class at 65.0 and use a class width of 5.
2. Construct a histogram.
3. Comment on the shape of the distribution.
4. Which state has the highest median income for two-earner households?
5. Which state has the lowest median income for two-earner households?

4.

The DATAfile Colleges contains a sample of 103 private colleges and universities. The data include the name of the college or university, the year the institution was founded, the tuition and fees (not including room and board) for the most recent academic year, and the percentage of full time, first-time bachelor’s degree-seeking undergraduate students who obtain their degree in six years or less (The World Almanac, 2012).

1. Construct a crosstabulation with Year Founded as the row variable and Tuition & Fees as the column variable. Use classes starting with 1600 and ending with 2000 in increments of 50 for Year Founded. For Tuition & Fees, use classes starting with 1 and ending 45000 in increments of 5000.
2. Compute the row percentages for the crosstabulation in part (a).
3. What relationship, if any, do you notice between Year Founded and Tuition & Fees?

5.

A zoo has categorized its visitors into three categories: member, school, and general. The member category refers to visitors who pay an annual fee to support the zoo. Members receive certain benefits such as discounts on merchandise and trips planned by the zoo. The school category includes faculty and students from day care and elementary and secondary schools; these visitors generally receive a discounted rate. The general category includes all other visitors. The zoo has been concerned about a recent drop in attendance. To help better understand attendance and membership, a zoo staff member has collected the following data in the DATAfile Zoo.

1. Construct a bar chart of total attendance over time. Comment on any trend in the data.
2. Construct a side-by-side bar chart showing attendance by visitor category with year as the variable on the horizontal axis.
3. Comment on what is happening to zoo attendance based on the charts from parts (a) and (b).