GRAVETTER_CH04_DEFINING STANDARD VARIATION AND VARIANCE

Question 1

TRUE OR FALSE: The standard deviation is the most commonly-used and the most important measure of variability.

Answer 1

TRUE.

Question 2

TRUE OR FALSE: Standard deviation uses the mean of the distribution as a reference point and measures variability by considering the distance between each score and the mean.

Answer 2

TRUE.

Question 3

TRUE OR FALSE: Standard deviation can describe whether the scores are clustered closely around the mean, or are widely scattered.

Answer 3

TRUE.

Question 4

What is the term for distance from the mean?

Answer 4

Deviation.

Question 5

THINK! What is the goal of getting the standard deviation?

Answer 5

The goal is to measure variability by finding the standard distance from the mean.

Question 6

THINK! How do you mathematically get deviation?

Answer 6

deviation score = X - μ

Question 7

THINK! What does the sign of the deviation score indicate?

Answer 7

It indicates the direction from the mean—that is, whether the score is located above (+) or below (-) the mean.

Question 8

THINK! When getting the average of all deviation scores, why does this add up to zero?

Answer 8

The mean serves as a balance point for the distribution. That is to say, the total of the distances above the mean is exactly equal to the total of the distance below the mean.

Question 9

TRUE OR FALSE: The sum of deviations is ALWAYS zero.

Answer 9

TRUE.

Question 10

THINK! Why is the sum of deviations of no use as a measure of variability?

Answer 10

Because it will always equal zero whether or not the scores and closely clustered or widely scattered.

Question 11

What term refers to the mean squared deviation?

Answer 11

Variance.

Question 12

THINK! How do you mathematically get the standard deviation?

Answer 12

Standard deviation = square root of the variance