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Chapter 1: Getting Started

Section 1.1

1. Individuals are people or objects included in the study, whereas a variable is a characteristic of the individual

that is measured or observed.

3. A parameter is a numerical measure that describes a population. A statistic is a numerical value that describes a

sample.

5. (a) The variable is the response regarding frequency of eating at fast-food restaurants.

(b) The variable is qualitative. The categories are the number of times one eats at fast-food restaurants.

(c) The implied population is responses for all adults in the United States.

7. (a) The variable is the nitrogen concentration (mg nitrogen/L water).

(b) The variable is quantitative because arithmetic operations can be applied to nitrogen concentration.

(c) The implied population is all the lakes in the wetlands.

9. (a) Length of time to complete an exam is a ratio level of measurement. The data may be arranged in order,differences and ratios are meaningful, and a time of 0 is the starting point for all measurements.

(b) Time of first class is an interval level of measurement. The data may be arranged in order, and differences

are meaningful.

(c) Major field of study is a nominal level of measurement. The data consist of names only.

(d) Course evaluation scale is an ordinal level of measurement. The data may be arranged in order.

(e) Score on last exam is a ratio level of measurement. The data may be arranged in order, differences andratios are meaningful, and a score of 0 is the starting point for all measurements.

(f) Age of studentis a ratio level of measurement. The data may be arranged in order, differences and ratios are

meaningful, and an age of 0 is the starting point for all measurements.

11. (a) Species of fish is a nominal level of measurement. Data consist of names only.

(b) Cost of rod and reelis a ratio level of measurement. The data may be arranged in order, differences and

ratios are meaningful, and a cost of 0 is the starting point for all measurements.

(c) Time of return home is an interval level of measurement. The data may be arranged in order, and

differences are meaningful.

(d) Guidebook ratingis an ordinal level of measurement. Data may be arranged in order.

(e) Number of fish caught is a ratio level of measurement. The data may be arranged in order, differences and

ratios are meaningful, and 0 fish caught is the starting point for all measurements.

(f) Temperature of the wateris an interval level of measurement. The data may be arranged in order, and

differences are meaningful.

13. (a) Answers vary. Ideally, weigh the packs in pounds using a digital scale that has tenths of pounds foraccuracy.

(b) Some students may refuse to allow the weighing.

(c) Informing students before class may cause students to remove items before class.

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4 Chapter 1

Section 1.2

1. In stratified samples, we select a random sample from each stratum. In cluster sampling, we randomly select

clusters to be included, and then each member of the selected cluster is sampled.

3. Sampling error is the difference between the value of the population parameter and the value of the sample

statistic that stems from the random selection process. Certainly larger boxes of cereal will cost more than smallboxes of cereal.

5. Simply use a computer or random-number table to randomly selected n students from the class after numbers

are assigned.

(a) Answers vary. Perhaps they are excellent students who make a special effort to get to class early.

(b) Answers vary. Perhaps they are busy students who are never on time for class.

(c) Answers vary. Perhaps students in the back row are introverted.

(d) Answers vary. Perhaps tall students generally are healthier.

7. Answers vary.

9. Answers vary.

11. (a) It is appropriate. Certainly we can roll a 1 more than once in 20 rolls. The fourth roll was 2.

(b) No, simulated rolls of the die are random events, and we certainly would expect a different sequence.

13. Answers vary.

15. (a) This technique is simple random sampling. Every sample of size n from the population has an equal chance

of being selected, and every member of the population has an equal chance of being included in the sample.

(b) This technique is cluster sampling. The state, Hawaii, is divided into ZIP codes. Then, within each of the 10

selected ZIP codes, allbusinesses are surveyed.(c) This technique is convenience sampling. This technique uses results or data that are conveniently and

readily obtained.

(d) This technique is systematic sampling. Every fiftieth business is included in the sample.

(e) This technique is stratified sampling. The population was divided into strata based on business type. Then a

simple random sample was drawn from each stratum.

Section 1.3

1. Answers vary. People with higher incomes likely will have high-speed Internet access, which will lead to

spending more time on-line. Spending more time on-line might lead to spending less time watching TV. Thus,spending less time watching TV cannot be attributed solely to high income or to high-speed Internet access.

3. (a) This is an observational study because observations and measurements of individuals are conducted in a

way that doesnt influence the response variable being measured.

(b) This is an experiment because a treatment is deliberately imposed on the bighorn sheep in order to observe

a possible change in heartworm prevention.

(c) This is an experiment because a treatment is deliberately imposed on the fishermen in order to observe a

possible change in the length of fish in the river.

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Chapter 1 5

(d) This is an observational study because observations of the turtles are conducted in a way that doesnt

change the response being measured.

5. (a) Use random selection to pick 10 calves to inoculate. After inoculation, test all calves to see if there is a

difference in resistance to infection between the two groups. No placebo is being used.

(b) Use random selection to pick nine schools to visit. After the police visits, survey all the schools to see if

there is a difference in views between the two groups. No placebo is being used.

(c) Use random selection to pick 40 volunteers for the skin patch with the drug. Then record the smokinghabits of all volunteers to see if a difference exists between the two groups. A placebo patch is used for the

remaining 35 volunteers in the second group.

7. Based on the information, Scheme A will be better because the blocks are similar. The plots bordering the river

should be similar, and the plots away from the river should be similar.

Chapter 1 Review

1. (a) Stratified

(b) All undergraduates at the specific campus studied

(c) The variable is number of hours worked. It is quantitative. It is a ratio.

(d) The variable is career applicability. It is qualitative. It is ordinal.

(e) It is a statistic.

(f) The nonresponse rate is 60%, and it most likely will introduce bias into the study because those who do not

answer may have different experiences from those who do answer.

(g) Probably not. These results are most applicable only to the campus in the study.

3. Using the random-number table, pick seven digits at random. Digits 0, 1, and 2 can correspond to Yes, and

digits 3, 4, 5, 6, 7, 8, and 9 can correspond to No. This will effectively simulate a random draw from a

population with 30% TIVO owners.

5. (a) This is an observational study because no treatments were applied.

(b) This is an experiment because a treatment was applied (test type) and the results then were compared.

7. Questions should be worded in a clear, concise, and unbiased manner. No questions should be misleading.

Common-sense rules should be stated for any numerical answers.

9. (a) This is an experiment; the treatment was the amount of light given to the colonies.

(b) We can assume that the normal-light group is the control group because this simulates normal light patterns

for the fireflies. Therefore, the constant-light group is the treatment group.

(c) Number of fireflies alive at the end of the study

(d) Ratio

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