147-sample2 - 1. Confounding with unrelated factors can be...

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1. Confounding with unrelated factors can be a serious problem in a. randomized controlled experiments. b. controlled experiments. c. observational studies. d. both (a) and (c). e. both (b) and (c). Answer (e) 2. In a series of repeated measurements, bias a. generally varies from measurement to measurement, sometimes up and sometimes down. b. is a systematic error in all measurements and affects all measurements the same way. c. can generally be ignored because of its random nature. d. can be readily detected by looking at the measurements themselves. e. satisfies both (a) and (c). Answer (b) 3. When data is collected from a series of repeated measurements, a. both the median and the standard deviation of the data are strongly affected by outliers in the data. b. the median is used as a numeric measure of the spread of the data. c. the standard deviation of the data can be used to estimate the bias in the measurements. d. chance error in the measurements affects all measurements the same way. e. none of the above statements are true. Answer (e) 4. A histogram a. is a graph which is used to summarize data. b. represents percents by area. c. consists of a set of blocks where the height of each block equals the percentage of cases in the corresponding class interval. d. satisfies both (a) and (b). e. satisfies all of the above. Answer (d) 5. When the histogram of a set of data follows the normal curve, a. about 68% of the data is within one standard deviation (SD) of the average. b. about 90% of the data is within two SDs of the average. c. about 95% of the data is within two SDs of the average.
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d. both (a) and (b) are true. e.
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147-sample2 - 1. Confounding with unrelated factors can be...

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