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Unformatted text preview: ts Percent Cost ($) Frequency Frequency 50­59 2 4 60­69 13 26 70­79 16 32 80­89 7 14 90­99 7 14 100­109 5 10 Total 50 100 Slide 36 Example: Hudson Auto Repair Graphical Summary (Histogram) 18 16 14 Frequency s 12 10 8 6 4 2 50 60 70 80 90 100 110 Parts Cost ($) Slide 37 Example: Hudson Auto Repair s Numerical Descriptive Statistics • The most common numerical descriptive statistic is the average (or mean). • Hudson’s average cost of parts, based on the 50 tune­ ups studied, is $79 (found by summing the 50 cost values and then dividing by 50). Slide 38 Statistical Inference s Statistical inference is the process of using data obtained from a small group of elements (the sample) to make estimates and test hypotheses about the characteristics of a larger group of elements (the population). Slide 39 Example: Hudson Auto Repair s Process of Statistical Inference 1. Population consists of all tune­ups. Average cost of parts is unknown. 2. A sample of 50 engine tune­ups is examined. 4. The value of the sample average is used to make an estimate of the population average. 3. The sample data provide a sample average cost of $79 per tune­up. Slide 40 End of Chapter 1 Slide 41 Exercises 1. The sample size a. can be larger than the population size b. is always smaller than the population size c. can be larger or smaller than the population d. is always equal to the size of the population Slide 42 s Correct Answer: b. is always smaller than the population size Slide 43 2. A population is a. the same as a sample b. the selection of a random sample c. the collection of all items of interest in a particular study d. none of the above Slide 44 s Correct Answer: c. the collection of all items of interest in a particular study Slide 45 3. The study of the methods of organization, summarization, and presentation of statistical data is referred to as a. inferential statistics b. descriptive statistics c. sampling d. none of the above Slide 46 s Correct Answer: b. descriptive statistics Slide 47 4. The process of making inferences about the characteristics of the population based on the sample information is termed a. descriptive statistics b. random sample c. statistical inference d. sampling Slid...
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