PSY2116B Quiz #2

A set of 10 scores has SS = 90. If the scores are a sample, the sample variance is ____ and if the scores are a population, the population variance is ____.

10; 9

A population of N = 100 scores has µ = 30 and s = 4. What is the population variance?

16

A population has SS = 100 and s2 = 4. How many scores are in the population?

25

For a perfectly symmetrical distribution with a median of 30, what is the value of the mean?

30

Which of the following statements CANNOT be true for a distribution of scores?

60% of the scores are above the median.

For a negatively skewed distribution with a mean of M = 20, what is the most probable value for the median?

Greater than 20

A distribution is positively skewed. Which is the most probable order, from smallest to largest, for the three measures of central tendency?

Mode, median, mean

True or False: A population of N = 5 scores has SS = 20 and variance = 4. If the 5 scores were a sample, the value of SS would still be 20 but the variance would be 5.

True

True or False: A sample with a variance of 25 has a standard deviation equal to 5 points.

True

True or False: To calculate the variance for a sample, SS is divided by df = n - 1.

True

True or False: A distribution of scores has a mean of 50, a median of 53, and a mode of 56. Based on this information it appears that the distribution is negatively skewed.

True

True or False: Changing the value of a score in a distribution will always change the value of the mean.

True

True or False: For a severely skewed distribution, the median often provides a better measure of central tendency than the mean.

True

True or False: The value for SS is always greater than or equal to zero.

True