Chapter 1

Question 1

statistics

Answer 1

A branch of mathematics that focuses on the organization, analysis, and interpretation of a group of numbers.

Question 2

descriptive statistics

Answer 2

Procedures for summarizing a group of scores

or otherwise making them more understandable.

Question 3

inferential statistics

Answer 3

Procedures for drawing conclusions based on
the scores collected in a research study (sample scores) but going
beyond them (to conclusions about a population).

Question 4

variable

Answer 4

Characteristic that can have different values.

Question 5

value

Answer 5

Number or category that a score can have.

Question 6

score

Answer 6

Particular person’s value on a variable.

Question 7

numeric value

Answer 7

Variable whose values are numbers (as opposed

to a nominal variable).

Question 8

equal-interval variable

Answer 8

A variable in which the numbers stand for approximately equal amounts of what is being measured.

Question 9

rank-order variable

Answer 9

Numeric variable in which the values are
ranks, such as class standing or place finished in a race; also called ordinal variable.

Question 10

nominal variable

Answer 10

Variable with values that are categories (that is, they

are names rather than numbers); same as categorical variable.

Question 11

level of measurement

Answer 11

Type of underlying numerical information

provided by a measure, such as equal-interval, rank-order, and nominal (categorical).

Question 12

frequency table

Answer 12

Ordered listing of the number of individuals having

each of the different values for a particular variable.

Question 13

interval

Answer 13

In a grouped frequency table, the range of values that are grouped together. (For example, if the interval size was 10, one of the intervals might be from 10 to 19.)

Question 14

grouped frequency table

Answer 14

Frequency table in which the number of

individuals (frequency) is given for each interval of values.

Question 15

histogram

Answer 15

Barlike graph of a frequency distribution in which the
values are plotted along the horizontal axis and the height of each bar
is the frequency of that value; the bars are usually placed next to each
other without spaces, giving the appearance of a city skyline.

Question 16

frequency distribution

Answer 16

Pattern of frequencies over the various values; what a frequency table or histogram describes.

Question 17

unimodal distribution

Answer 17

Frequency distribution with one value clearly having a larger frequency than any other.

Question 18

bimodal distribution

Answer 18

Frequency distribution with two approximately

equal frequencies, each clearly larger than any of the others.

Question 19

multimodal distribution

Answer 19

Frequency distribution with two or more

high frequencies separated by a lower frequency; a bimodal distribution is the special case of two high frequencies.

Question 20

rectangular distribution

Answer 20

Frequency distribution in which all values

have approximately the same frequency.

Question 21

symmetrical distribution

Answer 21

Distribution in which the pattern of frequencies

on the left and right side are mirror images of each other.

Question 22

skewed distribution

Answer 22

Distribution in which the scores pile up on

one side of the middle and are spread out on the other side; distribution that is not symmetrical.

Question 23

floor effect

Answer 23

Situation in which many scores pile up at the low end

of a distribution (creating skewness to the right) because it is not possible to have any lower score.

Question 24

ceiling effect

Answer 24

Situation in which many scores pile up at the high end

of a distribution (creating skewness to the left) because it is not possible to have a higher score.

Question 25

heavy-tailed distribution

Answer 25

Distribution that differs from a normal
curve by being too spread out so that a histogram of the distribution would have too many scores at each of the two extremes (“tails”).

Question 26

light-tailed distribution

Answer 26

Distribution that differs from a normal curve
by being too peaked or pinched so that a histogram of the distribution would have too few scores at each of the two extremes (“tails”).

Question 27

normal curve

Answer 27

Specific, mathematically defined, bell-shaped frequency distribution that is symmetrical and unimodal; distributions observed in nature and in research commonly approximate it.