Chapter 3

Question 1

Descriptive statistics

Answer 1

provide you with mathematical summaries of performance and performance characteristics

Question 2

Taxonomy of measurements

Answer 2

lowest - nominal
highest - ratio

Question 3

Nominal

Answer 3

a nominal scale is categorical in nature
- football positions
- gander
- type of car

There is no notion of order, magnitude, or size. Everyone within the group is assumed to have the same degree of the trait that determines their group.

Question 4

Ordinal

Answer 4

• ranking, as the finishing place in a race.
• things are ranked in order, but the difference between ranked positions are not comparable.

Question 5

Continuous

• interval
• ratio

Answer 5

numbers are said to be continuous in nature if they can be added, subtracted, multiplied, or divided and THE RESULTS HAVE MEANING.

Question 6

Interval numbers

Answer 6

• temperature or IQ
• a value of zero simply represents a point on a number line. It doesn’t mean that something doesn’t exist

Question 7

Ratio numbers

Answer 7

• have an absolute (true) zero
• weight or time

Question 8

Only INTERVAL AND RATIO numbers can be subjected to mathematical operations

Answer 8

True

Question 9

N

Answer 9

number of cases

Question 10

X (like x1 or x2)

Answer 10

any observed variable that you might measure

Question 11

the capital Greek letter sigma

Answer 11

the sum of

Question 12

Frequency distribution

Answer 12

a method of organizing data that involves noting the frequency with which various scores occurs

• norm-referenced comparison

Question 13

Percentile

Answer 13

is obtained by summing the present of scores that fall at or below the percentile you are calculating

• a percentile represents the present of observations at or below a given score

Example: if you achieved at the 90th percentile (P90), this simply means that your grade is higher than 90% of the people were tested.

Question 14

Central tendency

Answer 14

its where the scores tend to center

Question 15

Measures of central tendency

Answer 15

• mean
• median
• mode

Question 16

Mean

Answer 16

the arithmetical average, the sum of the scores divided by the number of scores

• the most stable one

Question 17

Median

Answer 17

• the middle score/ 50th percentile
• the most typical score in the distribution

Question 18

Mode

Answer 18

• the most frequent observed score
• the most unstable measure of central tendency
• but the most easily obtained one

Question 19

Skewness

Answer 19

the statistical term for the shape of a distribution

Question 20

Positive skewness

Answer 20

distribution has a tail toward the positive end (RIGHT) of the number line

Question 21

Negative skewness

Answer 21

distribution has a tail toward the negative end (LEFT) of the number line

Question 22

Kurtosis

Answer 22

the peakedness of a curve

Question 23

Mesokurtic

Answer 23

the normal curve (an average amount)

Question 24

Platykurtic

Answer 24

• the flatter curve
• has a negative kurtosis value

Question 25

Leptokurtic

Answer 25

• the steep curve (peaked)
• has a positive kurtosis value

Question 26

Variability

Answer 26

the spread of a distribution of scores

Measures of variability:
- range
- variance
- standard deviation

Question 27

Range

Answer 27

the high score - the low score
THE LEAST STABLE MEASURE OF VARIABILITY

Question 28

Variance (S2)

Answer 28

a measure of the spread of a set of scores based on the squared deviation of each score from the mean
THE MOST STABLE MEASURE OF VARIABILITY