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Unformatted text preview: AB103 – Statistical and Quantitative Methods Solutions  Tutorial 1 Chapter 1 (MBS) 1.2 Descriptive statistics utilizes numerical and graphical methods to look for patterns, to summarize, and to present the information in a set of data. Inferential statistics utilizes sample data to make estimates, decisions, predictions, or other generalizations about a larger set of data. 1.8 A population is a set of existing units such as people, objects, transactions, or events. A sample is a subset of the units of a population. 1.10 An inference without a measure of reliability is nothing more than a guess. A measure of reliability separates statistical inference from fortune telling or guessing. Reliability gives a measure of how confident one is that the inference is correct. 1.24 a. The variable of interest to the researchers is the rating of highway bridges. b. Since the rating of a bridge can be categorized as one of three possible values, it is qualitative. c. The data set analyzed is a population since all highway bridges in the U.S. were categorized. d. The data were collected observationally. Each bridge was observed in its natural setting. Chapter 2 (MBS) 2.4 a. The variable summarized in the table is ‘Reason for requesting the installation of the passengerside onoff switch.’ The values this variable could assume are: Infant, Child, Medical, Infant & Medical, Child & Medical, Infant & Child, and Infant & Child & Medical. Since the responses can only be classified into one of seven categories, the variable is qualitative. b. The relative frequencies are found by dividing the number of requests for each category by the total number of requests. For the category ‘Infant’, the relative frequency is 1,852/30,337 = .061. The rest of the relative frequencies are found in the table below: c. A pie chart of the data is d. There are 4 categories where Medical is mentioned as a reason: Medical, Infant & Medical, Child & Medical, and Infant & Child & Medical. The sum of the frequencies for these 4 categories is 8,377 + 44 + 903 + 135 = 9,459. The proportion listing Medical as one of the reasons is 9,459/30,337 = .312. 2.6 c. The category with the highest relative frequency of incidents is Engineering and Design. The category with the lowest relative frequency of incidents is Training and Communication. 2.29 a. The frequency histograms for the 2 years of SAT scores are: Histogram 2 4 6 8 10 12 14 16 900 940 980 1020 1060 1100 1140 1180 1220 More Scores  1990 Frequency Histogram 2 4 6 8 10 12 14 900 940 980 1020 1060 1100 1140 1180 1220 More Scores  2005 Frequency...
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 Spring '10
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