Chapter 3

Question 1

Central tendency

Answer 1

is a statistical measure to determine a single score that defines the center of a distribution. The goal of central tendency is to find the single score that is most typical or most representative of the entire group.

• attempts to identify the “average” or “typical” individual

Question 2

the mean

Answer 2

The mean for a distribution is the sum of the scores divided by the number of scores.

Question 3

population mean formula

Answer 3

mu (mean) = (sum of scores) (sigma X) /(number of scores) (N)

Question 4

sample mean

Answer 4

The distribution of sample means is the collection of sample means for all the possible random samples of a particular size (n) that can be obtained from a population.

Question 5

weighted mean

Answer 5

The average of two means, calculated so that each mean is weighted by the number of scores it represents.

Question 6

median

Answer 6

If the scores in a distribution are listed in order from smallest to largest, the median is the midpoint of the list. More specifically, the median is the point on the measurement scale below which 50% of the scores in the distribution are located.

Question 7

bimodal

Answer 7

a distribution with two modes

Question 8

mode

Answer 8

In a frequency distribution, the mode is the score or category that has the greatest frequency.

Question 8

multimodal

Answer 8

a distribution with more than two modes

Question 9

major mode

Answer 9

The taller peak of two modes with unequal frequencies.

Question 10

minor mode

Answer 10

The shorter peak of two modes with unequal frequencies.

Question 11

When to use the median

Answer 11

• extreme scores or skewed distributions - the median is relatively unaffected by extreme scores
• undetermined values
• open-ended distributions - A distribution is said to be open-ended when there is no upper limit (or lower limit) for one of the categories
• ordinal scale - You should recall that ordinal measurements allow you to determine direction (greater than or less than) but do not allow you to determine distance. - median is compatible with this

Question 12

When to use the mode

Answer 12

Nominal scales - Because nominal scales do not measure quantity (distance or direction), it is impossible to compute a mean or a median for data from a nominal scale. Therefore mode can only be used to describe central tendency for nominal data

Discrete variables - When these variables produce numerical scores, it is possible to calculate means. The mode, on the other hand, always identifies an actual score

Describing shape - The value of the mode (or modes) in this situation is that it gives an indication of the shape of the distribution as well as a measure of central tendency.

Question 13

line graph

Answer 13

A display in which points connected by straight lines show several different means obtained from different groups or treatment conditions. Also used to show different medians, proportions, or other sample statistics.