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Surveys & Experiments #1. Which of the following is not important in the design of experiments? Control of confounding variables. Randomization in assigning subjects to different treatments. Use of a lurking variable to control the placebo effect.
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Surveys & Experiments #1 Which of the following is not important in the design of experiments? • Control of confounding variables. • Randomization in assigning subjects to different treatments. • Use of a lurking variable to control the placebo effect. • Replication of the experiment using sufficient numbers of subjects. • All of the above are important in the design of experiments.
Surveys & Experiments #2 Sampling error occurs • when interviewers make mistakes resulting in bias. • because a sample statistic is used to estimate a population parameter. • when interviewers use judgment instead of random choice in picking the sample. • when samples are too small. • in all of the above cases.
Surveys & Experiments #3 What is a sample? • A measurable characteristic of a population. • A set of individuals having a characteristic in common. • A value calculated from raw data. • A subset of a population. • Non of the above.
Surveys & Experiments #4 A town has one high school, which buses students from urban, suburban, and rural communities. Which of the following samples is recommended in studying attitudes toward tracking of students in honors, regular, and below-grade classes? • Stratified sample • Systematic sample • Simple random sample (SRS) • Cluster Sample • Convenience Sample
Surveys & Experiments #5 Which among the following is most useful in establishing cause-and-effect relationships? • A complete census • A controlled experiment • A least squares regression line showing high correlation • A simple random sample (SRS) • A well-designed, well-conducted survey incorporating chance to ensure a representative sample
Inference #6 An engineer wishes to determine the quantity of heat being generated by a particular electronic component. If she knows that the standard deviation is 2.4, how many of these components should she consider to be 99% sure of knowing the mean quantity to within ±0.6? (A) 27 (B) 62 (C) 87 (D) 212 (E) 107
Inference #7 In general, how does tripling the sample size change the confidence interval size? • It triples the interval size. • It divides the interval size by 3. • It multiplies the interval size by 1.732. • It divides the interval size by 1.732. • This question cannot be answered without knowing the sample size.
Inference #8 The weight of an aspirin tablet is 300 milligrams according to the bottle label. An FDA investigator weighs a SRS of seven tablets, obtains weights of 299, 300, 305, 302, 299, 301, and 303, and runs a hypothesis test of the manufacturer’s claim. Which of the following gives the P-value of this test? (A) P (t > 1.54) with df = 6 (B) 2P (t > 1.54) with df = 6 (C) P (t > 1.54) with df = 7 (D) 2P (t > 1.54) with df = 7 (E) 0.5P (t > 1.54) with df = 7
Inference #9 Which of the following will increase as the sample size increases? • The probability of a Type I error. • The probability of a Type II error. • The power of the test. (A) I only (B) II only (C) III only (D) II and III (E) None
Inference #10 A building inspector believes that the percentage of new construction with serious code violations may be even greater than the previously claimed 7%. She conducts a hypothesis test on 200 new homes and finds 23 with serious code violations. Is this strong evidence against the .07 claim? • Yes, because the P-value is .0062. • Yes, because the P-value is 2.5. • No, because the P-value is only .0062. • No, because the P-value is over 2.0. • No, because the P-value is .045.
Probability #11 Suppose that for a certain Caribbean island in any 3-year period the probability of a major hurricane is .25, the probability of water damage is .44, and the probability of both a hurricane and water damage is .22. What is the probability of water damage given that there is a hurricane? • .47 • .50 • .69 • .88 • .91
Probability #12 Suppose X and Y are random variables with μx = 32, σx = 5, μy = 44, and σy = 12. What are the mean and standard deviation of the random variable X + Y? • μx+y = 76, σx+y = 13 • μx+y = 76, σx+y = 8.5 • μx+y = 76, σx+y = 17 • μx+y = 38, σx+y = 17 • There is insufficient information to answer this question.
Probability #13 According to one poll, 12% of the public favor legalizing all drugs. In a simple random sample of six people, what is the probability that at least one person favors legalization? • .380 • .464 • .536 • .620 • .844
Probability #14 If 70% of all drivers wear seatbelts, what is the probability that a police roadblock finds the first unbelted driver in the third car stopped? • .15 • .19 • .44 • .66 • .70
Probability #15 At a warehouse sale, 100 customers are invited to choose one of 100 identical boxes. Five boxes contain $700 color television sets, 25 boxes contain $540 camcorders, and the remaining boxes contain $260 cameras. Find the expected value of the prize. • $260 • $352 • $500 • $540 • $699
Regression #16 Suppose there is a correlation of r = 0.9 between number of hours per day students study and GPAs. Which of the following is a reasonable conclusion? • 90% of students who study receive high grades. • 90% of students who receive high grades study a lot. • 81% of the variation in GPAs can be explained by variation in number of study hours per day. • 90% of the variation in GPAs can be explained by variation in number of study hours per day. • 10% of the variation in GPAs cannot be explained by variation in number of study hours per day.
Regression #17 Which of the following statements about the correlation r are true? I. It is not affected by changes in the measurement units of the variables. II. It is not affected by which variable is called x and which is called y. III. It is not affected by extreme values. (A) I and II (B) I and III (C) II and III (D) I, II, and III (E) None
Regression #18 A study investigating the association between a student’s reading level (x) and his/her score on a math achievement test (y) found the correlation to be 0.80. Reading levels had a mean of 9 and SD of 1.5, while math scores had a mean of 450 and SD of 90. If Bonnie’s reading level is 12, what would these results predict her math achievement score to be? (A) 453 (B) 522 (C) 565 (D) 594 (E) 630
Regression #19 A scatterplot of 10 data points produces a regression line with SE(b1) = 1.8. The margin of error for a 95% confidence interval for β is (A) 1.313 (B) 3.348 (C) 3.528 (D) 4.072 (E) 4.151
Regression #20 Which of the following statements about residuals are true? I. The regression line for a residual plot is a horizontal line. II. A scattered residual plot indicates a model with high predictive power. III. A definite pattern in the residual plot is an indication that a nonlinear model will show a better fit to the data than the straight regression line. (A) I and II (B) I and III (C) II and III (D) I, II, and III (E) None
Exploring Data #21 Which of the following are affected by outliers? • Mean • Median • Standard Deviation • Range • Interquartile Range (A) I, II, and V (B) II and IV (C) I, III, and IV (D) III and IV (E) I and V
Exploring Data #22 The longevity of people living in a certain locality has a standard deviation of 14 years. What is the mean longevity if 30% of the people live longer than 75 years? Assume a normal distribution for life spans. • 61.00 • 67.65 • 74.48 • 82.35 • The mean cannot be computed from the information given.
Exploring Data #23 If all the values of a data set are the same, all of the following must equal zero except for which one? • Mean • Standard deviation • Variance • Range • Interquartile range
Exploring Data #24 At the annual doctor’s checkup for a 3-year-old girl, her parents are told that she is one standard deviation above the mean height for her age. Assume that heights for 3-year-old girls are normally distributed What percentile is she in height? • 16th • 32nd • 34th • 68th • 84th
Exploring Data #25 When there are multiple gaps and clusters, which of the following is the best choice to give an overall picture of a distribution? • Mean and standard deviation • Median and interquartile range • Boxplot with its five-number summary • Stemplot or histogram • None of the above are really helpful in showing gaps and clusters.
