1. Fill in the blank. The range, standard deviation, and variance, are all measures of what________________________. Not to be confused with measures of central tendency or measures of centers.
2. Comparing variation. Which do you think has more variation: the incomes of a simple random sample of 1000 adults selected from the general population, or the incomes of a simple random sample of 1000 statistics teachers? Why?
3. Unusual value? The systolic blood pressures of 40 women have a mean of 110.8 mm Hg and a standard deviation of 17.1 mm Hg. The higher systolic blood pressure measurement in this sample is 181 mm Hg. In this context, is a systolic blood pressure of 181 mm Hg "unusual"? Why or why not? Hint: If the value in question is within two standard deviations of the mean, the value is usual (see Empirical Rule).