For Exercise 2.91, see page 106; for 2.92 and 2.93, see pages 106–107; for 2.94 to 2.96, see page 108; for 2.97 to 2.99, see page 109; and for 2.100 and 2.101, see pages 111–112.
2.102 Remote deposit capture
The Federal Reserve has called remote deposit capture (RDC) “the most important development the [U.S.] banking industry has seen in years.” This service allows users to scan checks and to transmit the scanned images to a bank for posting.16 In its annual survey of community banks, the American Bankers Association asked banks whether or not they offered this service.17 Here are the results classified by the asset size (in millions of dollars) of the bank:
rdc
Offer RDC | ||
---|---|---|
Asset size ($ in millions) |
Yes | No |
Under $100 | 63 | 309 |
$101 to $200 | 59 | 132 |
$201 or more | 112 | 85 |
Summarize the results of this survey question numerically and graphically. Write a short paragraph explaining the relationship between the size of a bank, measured by assets, and whether or not RDC is offered.
2.103 How does RDC vary across the country?
The survey described in the previous exercise also classified community banks by region. Here is the table of counts:18
Offer RDC | ||
---|---|---|
Region | Yes | No |
Northeast | 28 | 38 |
Southeast | 57 | 61 |
Central | 53 | 84 |
Midwest | 63 | 181 |
Southwest | 27 | 51 |
West | 61 | 76 |
Summarize the results of this survey question numerically and graphically. Write a short paragraph explaining the relationship between the location of a bank, measured by region, and whether or not remote deposit capture is offered.
2.103
Only 37% of all banks offer RDC. Regions with high percentages of banks offering RDC are Southeast (48.31%), West (44.53%), and Northeast (42.42%). Midwest (25.82%) has a low percentage of banks offering RDC.
2.104 Exercise and adequate sleep
A survey of 656 boys and girls, ages 13 to 18, asked about adequate sleep and other health-related behaviors. The recommended amount of sleep is six to eight hours per night.19 In the survey, 54% of the respondents reported that they got less than this amount of sleep on school nights. The researchers also developed an exercise scale that was used to classify the students as above or below the median in how much they exercised. Here is the table of counts with students classified as getting or not getting adequate sleep and by the exercise variable:
sleep
114
Exercise | ||
---|---|---|
Enough sleep | High | Low |
Yes | 151 | 115 |
No | 148 | 242 |
2.105 Adequate sleep and exercise
Refer to the previous exercise.
sleep
2.105
(a) For those who get enough sleep, 56.8% are high exercisers and 43.2% are low exercisers. (b) For those who don't get enough sleep, 37.9% are high exercisers and 62.1% are low exercisers. (c) Those who get enough sleep are more likely to be high exercisers than those who don't get enough sleep.
2.106 Full-time and part-time college students
The Census Bureau provides estimates of numbers of people in the United States classified in various ways.20 Let's look at college students. The following table gives us data to examine the relation between age and full-time or part-time status. The numbers in the table are expressed as thousands of U.S. college students.
colstud
Status | ||
---|---|---|
Age | Full-time | Part-time |
15–19 | 3388 | 389 |
20–24 | 5238 | 1164 |
25–34 | 1703 | 1699 |
35 and over | 762 | 2045 |
2.107 Condition on age
Refer to the previous exercise.
colstud
2.107
(a) For Age 15 to 19: 89.7% are Full-time and 10.3% are Part-time. For Age 20 to 24: 81.82% are Full-time and 18.18% are Part-time. For Age 25 to 34: 50.06% are Full-time and 49.94% are Part-time. For Age 35 and Over: 27.15% are Full-time and 72.85% are Part-time. (d) Students aged 15–24 are much more likely to be Full-time, while students aged 35 and over and more likely to be Part-time. Students aged 25–34 are about equally likely to be Full- or Part-time students. (e) Because there are only 2 categories for Status, if we are given the percentage of Full-time students, the percentage of Part-time students must be 100% minus the percentage for Full-time. (f) Both are valid descriptions; it mostly depends on the condition in which you are interested. If we are interested in a particular age group, the current analysis likely has more meaning, whereas if we are interested in a particular status, the previous analysis has more meaning.
2.108 Lying to a teacher
One of the questions in a survey of high school students asked about lying to teachers.21 The accompanying table gives the numbers of students who said that they lied to a teacher about something significant at least once during the past year, classified by sex.
lying
Sex | ||
---|---|---|
Lied at least once | Male | Female |
Yes | 6067 | 5966 |
No | 4145 | 5719 |
2.109 Trust and honesty in the workplace
The students surveyed in the study described in the previous exercise were also asked whether they thought trust and honesty were essential in business and the workplace. Here are the counts classified by sex:
trust
Sex | ||
---|---|---|
Trust and honesty are essential | Male | Female |
Agree | 9,097 | 10,935 |
Disagree | 685 | 423 |
Answer the questions given in the previous exercise for this survey question.
2.109
There were 21,140 students total; 20,032 agree and 1,108 disagree; 11,358 female and 9,782 male. 96% of females and 93% of males agreed that trust and honesty are essential. A slightly higher percentage of females said that trust and honesty are essential.
115
2.110 Class size and course level
College courses taught at lower levels often have larger class sizes. The following table gives the number of classes classified by course level and class size.22 For example, there were 202 first-year level courses with between one and nine students.
csize
Class size | |||||||
---|---|---|---|---|---|---|---|
Course level |
1–9 | 10–19 | 20–29 | 30–39 | 40–49 | 50–99 | 100 or more |
1 | 202 | 659 | 917 | 241 | 70 | 99 | 123 |
2 | 190 | 370 | 486 | 307 | 84 | 109 | 134 |
3 | 150 | 387 | 314 | 115 | 96 | 186 | 53 |
4 | 146 | 256 | 190 | 83 | 67 | 64 | 17 |
2.111 Hiring practices
A company has been accused of age discrimination in hiring for operator positions. Lawyers for both sides look at data on applicants for the past three years. They compare hiring rates for applicants younger than 40 years and those 40 years or older.
hiring
Age | Hired | Not hired |
---|---|---|
Younger than 40 | 82 | 1160 |
40 or older | 2 | 168 |
2.111
(a) For younger than 40: 6.6% were hired, 93.4% were not. For 40 or older: 1.18% were hired, 98.82% were not. (c) The percentage of hired is greater for the younger than 40 group; the company looks like it is discriminating. (d) Education could be different among groups, making them more or less qualified.
2.112 Nonresponse in a survey of companies
A business school conducted a survey of companies in its state. It mailed a questionnaire to 200 small companies, 200 medium-sized companies, and 200 large companies. The rate of nonresponse is important in deciding how reliable survey results are. Here are the data on response to this survey:
nresp
Small | Medium | Large | |
---|---|---|---|
Response | 124 | 80 | 41 |
No response | 76 | 120 | 159 |
Total | 200 | 200 | 200 |
2.113 Demographics and new products
Companies planning to introduce a new product to the market must define the “target” for the product. Who do we hope to attract with our new product? Age and sex are two of the most important demographic variables. The following two-way table describes the age and marital status of American women.23 The table entries are in thousands of women.
agegen
Marital status | ||||
---|---|---|---|---|
Age (years) | Never married |
Married | Widowed | Divorced |
18 to 24 | 12,112 | 2,171 | 23 | 164 |
25 to 39 | 9,472 | 18,219 | 177 | 2,499 |
40 to 64 | 5,224 | 35,021 | 2,463 | 8,674 |
984 | 9,688 | 8,699 | 2,412 |
2.113
(a) 27,792 never married; 65,099 married; 11,362 widowed; 13,749 divorced. (b) Marginal distributions:
Percent | Never- Married |
Married | Widowed | Divorced | Total |
---|---|---|---|---|---|
18To24 | 10.26 | 1.84 | 0.02 | 0.14 | 12.3 |
25To39 | 8.03 | 15.44 | 0.15 | 2.12 | 25.7 |
40To64 | 4.43 | 29.68 | 2.09 | 7.35 | 43.5 |
65And-Over | 0.83 | 8.21 | 7.37 | 2.04 | 18.5 |
Total | 23.55 | 55.17 | 9.63 | 11.65 | 100 |
(c) Conditional distribution given Marital Status:
Percent | Never- Married |
Married | Widowed | Divorced |
---|---|---|---|---|
18To24 | 43.58 | 3.33 | 0.2 | 1.19 |
25To39 | 34.08 | 27.99 | 1.56 | 18.18 |
40To64 | 18.8 | 53.8 | 21.68 | 63.09 |
65AndOver | 3.54 | 14.88 | 76.56 | 17.54 |
Total | 100 | 100 | 100 | 100 |
Conditional distribution given Age:
Percent | Never- Married |
Married | Widowed | Divorced | Total |
---|---|---|---|---|---|
18To24 | 83.7 | 15 | 0.16 | 1.13 | 100 |
25To39 | 31.19 | 60 | 0.58 | 8.23 | 100 |
40To64 | 10.17 | 68.16 | 4.79 | 16.88 | 100 |
65And-Over | 4.52 | 44.48 | 39.93 | 11.07 | 100 |
(e) More than half of women are married; of that group, age 40 to 64 is the most common followed by 25 to 39. Almost 25% never married, but most of that group is represented by younger age groups. Widowed and Divorced have relatively small percentages across the board, though the 65 and Over group is most likely to be widowed and the 40 to 64 group is most likely to be divorced.
2.114 Demographics, continued
agegen
2.115 Demographics and new products—men
Refer to Exercises 2.113 and 2.114. Here are the corresponding counts for men:
agegen
116
Marital status | ||||
---|---|---|---|---|
Age (years) | Never married |
Married | Widowed | Divorced |
18 to 24 | 13,509 | 1,245 | 6 | 63 |
25 to 39 | 12,685 | 16,029 | 78 | 1,790 |
40 to 64 | 6,869 | 34,650 | 760 | 6,647 |
685 | 12,514 | 2,124 | 1,464 |
Answer the questions from Exercises 2.113 and 2.114 for these counts.
2.115
33,748 never married; 64,438 married; 2,968 widowed; 9,964 divorced. Joint and marginal distributions:
Percent | Never- Married |
Married | Widowed | Divorced | Total |
---|---|---|---|---|---|
18To24 | 12.16 | 1.12 | 0.01 | 0.06 | 13.3 |
25To39 | 11.42 | 14.43 | 0.07 | 1.61 | 27.5 |
40To64 | 6.18 | 31.18 | 0.68 | 5.98 | 44 |
65And-Over | 0.62 | 11.26 | 1.91 | 1.32 | 15.1 |
Total | 30.37 | 57.99 | 2.67 | 8.97 | 100 |
Conditional distribution given Marital Status:
Percent | Never- Married |
Married | Widowed | Divorced |
---|---|---|---|---|
18To24 | 40.03 | 1.93 | 0.2 | 0.63 |
25To39 | 37.59 | 24.88 | 2.63 | 17.96 |
40To64 | 20.35 | 53.77 | 25.61 | 66.71 |
65And-Over | 2.03 | 19.42 | 71.56 | 14.69 |
Total | 100 | 100 | 100 | 100 |
Conditional distribution given Age:
Percent | Never- Married |
Married | Widowed | Divorced | Total |
---|---|---|---|---|---|
18To24 | 91.14 | 8.4 | 0.04 | 0.43 | 100 |
25To39 | 41.48 | 52.41 | 0.26 | 5.85 | 100 |
40To64 | 14.04 | 70.82 | 1.55 | 13.59 | 100 |
65AndOver | 4.08 | 74.55 | 12.65 | 8.72 | 100 |
More than half of men are married; of that group, age 40 to 64 is the most common followed by 25 to 39 and 65 and Over. More than 30% never married, very few of which are 65 and Over. Fewer than 3% of men are widowed, and the vast majority are 65 and Over. About 9% are divorced, two-thirds in the 40 to 64 age group.
2.116 Discrimination?
Wabash Tech has two professional schools, business and law. Here are two-way tables of applicants to both schools, categorized by sex and admission decision. (Although these data are made up, similar situations occur in reality.)
disc
Business | ||
---|---|---|
Admit | Deny | |
Male | 480 | 120 |
Female | 180 | 20 |
Law | ||
---|---|---|
Admit | Deny | |
Male | 10 | 90 |
Female | 100 | 200 |
2.117 Obesity and health
Recent studies have shown that earlier reports underestimated the health risks associated with being overweight. The error was due to lurking variables. In particular, smoking tends both to reduce weight and to lead to earlier death. Illustrate Simpson's paradox by a simplified version of this situation. That is, make up tables of overweight (yes or no) by early death (yes or no) by smoker (yes or no) such that
2.118 Find the table
Here are the row and column totals for a two-way table with two rows and two columns:
60 | ||
60 | ||
70 | 50 | 120 |
Find two different sets of counts , , , and for the body of the table that give these same totals. This shows that the relationship between two variables cannot be obtained from the two individual distributions of the variables.