Stat HW1

# Stat HW1 - Statistics 285 Solutions to HW #1 Problems 1.14...

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Statistics 285 Solutions to HW #1 Problems 1.14 a. The two variables measured are ‘type of credit card used’ and ‘amount of purchase.’ ‘Type of credit card used’ is qualitative. It has no meaningful number associated with it, only the name of the card used. ‘Amount of purchase’ is quantitative. It has a meaningful number associated with it. b. In Study 1, it says that all purchases were tracked. Thus, the data represent a population. 1.22 a. The data collection method used is a designed experiment. b. The experimental units in the study are the 50,000 smokers. c. The variable of interest is the age at which the scanning method first detects a tumor. Since this is a meaningful number, this variable is quantitative. d. The population of interest is the set of all smokers in the U.S. The sample of interest is the set of 50,000 smokers surveyed. e. The researchers want to compare the age at first detection for the 2 methods to see if one is more sensitive than the other. 1.26 a. The population of interest would be the set of all students. The sample of interest would be the students participating in the experiment. The variable measured in this study is whether the student would spend money on repairing a very old car or not. b. The data-collection method used was a designed experiment. The students participating in the experiment were randomly assigned to one of three emotional states and then asked a question. c. The researcher could estimate the proportion of all students in each of the three emotional states who would spend money to repair a very old car. d. Some other factors that might affect the reliability of the inference drawn are whether the students in the experiment were representative of all students. It is stated that the sample was made up of volunteer students. Chances are that these volunteer students were not representative of all students. In addition, if these students were all from the same school, they probably would not be representative of the population of students either.

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2.4 a. The relative frequency for each response category is found by dividing the frequency by the total sample size. The relative frequency for the category “Insurance Companies” is 869/2119 = .410. The rest of the relative frequencies are found in a similar manner and are reported in the table. Most responsible for rising health-care costs Number responding Relative Frequencies Insurance companies 869 869/2119 = .410 Pharmaceutical companies 339 339/2119 = .160 Government 338 338/2119 = .160 Hospitals 127 127/2119 = .060 Physicians 85 85/2119 = .040 Other 128 128/2119 =.060 Not at all sure 233 233/2119 =.110 TOTAL 2,119 1.00 b. Using MINITAB, the relative frequency bar chart is: Category Count Not sure Other Physicians Hospitals Government Pharm Insurance Co 40 30 20 10 0 Chart of Category 13 2
c. Using MINITAB, the Pareto diagram is: Category Relative Frequency Physicians Other Hospitals Not sure Pharm Government Insurance Co. .40

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Stat HW1 - Statistics 285 Solutions to HW #1 Problems 1.14...

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