课程名称︰统计导论 课程性质︰数学系选修 课程教师︰江金仓 开课学院：理学院 开课系所︰数学系 考试日期（年月日）︰2016.11.7 考试时限（分钟）：110 试题 : Introduction to Statistics (Midterm) 1.(20%) Explain the following terms: (1a) interval measurement scale variable. (1b) systematic sampling. (1c) outlier. (1d) ogive. (1e) matched-paired design. 2.(20%) Identify each of the studies in the appendix as a survey, an experimental study, a prospective observational study, a retrospective observational study, a case-control design in an observational study, or a case study. 3.(10%) Compute the interquartile of the grouped data with f_1,f_2,...,f_g being the frequencies of the g classes [L,L+h), [L+h,L=2h),..., [L+(g-1)h,U], where U=L+gh. 4.(10%) Consider the data of thirteen ninth-year students in Sydney using conventional instructional meterial.The number of seconds, required to arrive at a solution, are recorded for the students. Each student was allotted at most 5 minutes to answer a question. What is the median time for these students to arrive at a solution? Data: 130, 139, 146, 150, 161, 177, 228, 242, 265, 300+, 300+, 300+, 300+. (Note: t+ represents the required time more than t seconds.) 5.(10%) Let r_XY be the Pearson correlation coefficient of the sample {(X_1,Y_1),...,(X_n,Y_n)}. Show that |r_XY|≦1. 6.(5%)(5%)(5%) Give data with three points (X_1,Y_1), (X_2,Y_2), and (X_3,Y_3) so that the corresponding sample correlation coefficients are 0, 1, and -1, respectively. 7.(7%)(8%) Assume that the GRE score has a symmetric distribution with mean of 497 and standard deviation of 115. Find the median GRE score and the Z- score for the GRE score of 450. ◎ Appendix 1. Bumpus Data on natural selection -An observational study In a 1989 biology lecture at Woods Hole, Massachusetts, Hermon Bumpus remained his audience that the process of natural selection of evolutionary change was an unproved theory. As evidence in support selection, he presented measurements on house sparrows brought to the Anatomical Laboratory of Brown University after an uncommonly severe winter storm. Research interest: Do humerus (arm bone) lengths tend to be different for survivors than for those that perished? If so, how large is the difference? Data collection: The humerus lengths for the 24 adult male sparrows that perished and for the 35 adult males that survived were recorded. 2. Anatomical Abnormalities associated with Schizophrenia Early studies, based largely on postmortem analysis, suggest that the size of certain areas of the brain may be different in persons afflicted with schizophrenia than in others. The researchers used magnetic resonance imaging (MRI) to measure the volume of several regions inside the twin's brain. Research interest: What is the magnitude of the difference in volume of the left hippocampus between the unaffected and the affected individuals? Can the observed difference be attributed to chance? Data collection: In a 1990 article, researchers conducted a study that controlled for gentic and socioeconomic differences by examining 15 pairs of monozygotic twins, where one of the twins was schizophrenic and other was not. 3. Bird keeping and lung cancer Research interest: A 1972-1981 health survey in Hague, Netherlands, discovered an association between keeping pet birds and increased risk of lung cancer. To investigate bird keeping as risk of factor, researchers conducted a case- control study of patients in 1985 at four hospitals in Hague. Data collection: They identified 49 cases of lung cancer patients who were registered with a general praceice, who were 65 or younger, and who had resided in the city since 1965. They also selected 98 controls from a population of residents having the same general age structure. 4. Diet Restriction and Longevity 349 female mice were randomly assigned to one of the following six treatment groups. ┌────────────────┐ ┌────────────────┐ │N/N85 │ │NP │ │Normal (Control) │ │Ate as much as they pleased of a│ │Normal 85 kcal/wk │ (e) │non-purified,standard diet │ │ (57)│───│ (49)│ └────────────────┘ └────────────────┘ │ │(a) │ ┌────────────────┐ ┌────────────────┐ │N/R50 │ │N/R50 lopro │ │Before weaning: normal diet │ │Normal │ │After weaning: 50 kcal/wk │ (d) │50 kcal/wk & decreasing dietary │ │(reduced-calorie) (56)│───│protein content (56)│ └────────────────┘ └────────────────┘ │ ＼ │(b) ＼(c) │ ＼ ┌────────────────┐ ┌────────────────┐ │R/R50 │ │N/R40 │ │50 kcal/wk │ │Normal │ │50 kcal/wk │ │40 kcal/wk │ │ (56)│ │(severely reduced diet) (60)│ └────────────────┘ └────────────────┘ (a) Does reduce from 85 to 50 kcal/wk increase lifespan? (b) Is there an effect of pre-wearning diet? (c) Does further reduction from 50 to 40 kcal/wk increase lifespan more? (d) Does reduction in protein, with same calories, change lifetime distribution? (e) Does control mice have same lifetimes as the the laboratory mice? --

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