Q1. In any distribution, about 78 percent of all the cases fall within: A. one standard deviation of the mean B. two standard deviations of the mean C. three standard deviations of the mean D. none of the above Q2. Which of the following statements is not true? A. Observations are the units upon which researchers conduct measurements. B. Variables are the characteristics researchers measure C. Values are the unrealized measurements B. None of the above Q3. Disjoint events are: A. independent B. not independent C, both dependent and independent D. none of the above Q4. Which of the following is true of probability? A. Probability refers to the proportion of times an event is expected to occur in the short run. B. Probability refers to the proportion of times an event must occur in a long run. C. Probability refers to the proportion of times an event is predicted to occur in a long run. D. None of the above Q5. Which type of sampling method randomly selects clusters consisting of smaller subunits? A. Stratified random sample. B. Simple random sample C. Proportionate random sample D. None of the above