Exam 4: Measures of Central Tendency and Variability

A statistics class taught by Dr. X had 30 students who obtained an average test score of 82.5. A class taught by Dr. Why had 20 students who ended up with an average score of 79.6. Dr. Zee (you guessed it) had 23 students who obtained an average score of 96.0. What was the average score for all the students combined?

If the distribution is symmetrical, which is the best measure of central tendency?

Consider a distribution with N = 100, = 50, and = 9875. If 10 new scores of 50 were added to the distribution, what would happen to the sum of squares?

The most commonly encountered measure of central tendency is the _________.

A car company wanted to know how many miles per gallon an experimental car got after a series of tests. The following data were obtained. Miles per gallon: 31.2, 28.6, 36.4, 37.3, 30.1, 29.0, 32.7, 31.9

The mean must have a value equal to one of the scores in the distribution.

Assume that the standard deviation of one distribution equals 15 and the standard deviation of another distribution is equal to 23. Which of the following distributions is more likely to represent the case where s = 15 if the other distribution's standard deviation equals 23?

If a constant of 5 is subtracted from all of the scores, the standard deviation _________.

Consider the following two sets of scores. X : 80, 70, 55, 63, 72 Y : 50, 52, 59, 60

Assume one has a set of 35 scores with = 100 and s = 9. If 5 scores, each equal to 100 were added to the distribution, what effect would this have on ?

An instructor decides to weight the scores on three tests differently. The first test is weighted only half as much as the second test. The third test is the final and it is weighted twice as much as the second test. The mean grade on the first test was 68, the mean of the second test was 75, and the mean on the third test was 80. What is the mean grade for all three tests, assuming the same number of students took all the exams?

Identify four properties of the mean and give an example of each.

The mean is the most sensitive measure of central tendency to extreme scores.

The mean is the same as the arithmetic average.

Consider the following scores: 21, 22, 22, 0.1, 20, 25, 28, 26, 23, 19, 0.5. Which of the measures listed below would give the best description of the central tendency of these scores?

An industrial psychologist observed 8 drill-press operators for one working day. She recorded the number of times each operator pressed the "faster" button instead of the "stop" button to determine whether the design of the control panel was contributing to the high rate of accidents in the plant. The resulting scores were as follows: 5, 2, 8, 2, 3, 2, 4, 12 The mode for this distribution is _________.

A history professor gives a quiz to his class and records the following scores: 13, 11, 11, 9, 12, 13, 16, 14, 11, 10, 8, 13, 20. The median for this distribution is _________.

A deviation score is the same thing as a raw score.

Which of the following do (does) not measure average dispersion?

Write the number of the symbol shown in Column 1 in the space provided to the left of the term in Column 2 that it represents.