C5 Quiz

• A measure of variability provides information about individual differences.
• Eliminating some scores from a point near the mean will increase the standard deviation.
• Consider the two scores, 4 and 8.  SS = 8.
• SS/n = variance.
• At one stage of calculation we have  S= the square root of (-36). From this, we know that we have made an error computation.
• A frequency distribution of observations is approximately normal with  and  The middle 95% of the cases will fall (approximately) between 50 and 70.
• A distribution of 80 observations is approximately normal with a mean of 120 and a range of 50. Which of the following is the most reasonable value for the standard deviation? 10
• A frequency distribution of scores is normal with a mean of 80 and a standard deviation of 9. Roughly two thirds of the cases fall between scores of 71 and 89.
• In a normal distribution, we expect about what percent of scores to fall above a score three standard deviations below the mean? i. e., above x-bar - 3s. more than 99%
• If performance is normally distributed, and grades of A are given to those who score at 1 standard deviation above the mean or better, we should expect about what proportion of students to earn an A? 16%
• Given:  x-bar1 is < x-bar2 and  S1 > S2 You therefore know that S pooled  is closer to S2  than S1.
• Seniors at two universities take the Graduate Record Examination. Students from the first institution earn a mean of 520; those from the second, 505. The standard deviation of this test of 100. Would you say that seniors at the first institution seem to be a little superior to those at the second.