chapter 3

Question 1

Deciles.

Answer 1

The points that divide a distribution of scores into 10ths.

Question 2

Mean

Answer 2

The arithmetic average of the scores. represents the mean of a sample, and m, the mean of a population.

Question 3

Measures of central tendency.

Answer 3

Statistics that summarize a distribution of scores by reporting the most typical or representative value of the distribution.

Question 4

Median

Answer 4

The point in a distribution of scores above and below which exactly half of the cases fall.

Question 5

Mode

Answer 5

The most common value in a distribution or the largest category of a variable.

Question 6

Percentile

Answer 6

A point below which a specific percentage of the cases fall

Question 7

Quartiles

Answer 7

The points that divide a distribution into quarters.

Question 8

(uppercase Greek letter sigma)

Answer 8

“The summation of.”

Question 9

Skew

Answer 9

The extent to which a distribution of scores has a few scores that are extremely high A>- (positive skew) or extremely low -<A (negative skew).

Question 10

Xi (“X-sub-i ”).

Answer 10

Any score in a distribution.

Question 11

the purpose of the measure of central tendencies

Answer 11

Each reports some information about the most typical or representative value in a distribution. Appropriate use of these statistics permits the researcher to report important information about an entire distribution of scores in a single, easily understood number.

Question 12

the mode on variables

Answer 12

reports the most common score and is used most appropriatly with nominally measured variable

Question 13

the median on report

Answer 13

report the score theat is the exact center of the distribution, –> ordinal level & interval ratio

Question 14

the mean

Answer 14

interval ratio

Question 15

the mean when the distribution is skewed

Answer 15

the mean is affected by every scores numeric outcome unlike the mode and the median

when positively skewed ( extreme high scores - A>- ) the mean always be greater than the mean

when negatively skewed -<A ( the mean will be lowed in the value than the median )

Question 16

the most appropriate way to measure of central tendency of each level of measurement

nominal - ordinal - interval & ratio

Answer 16

nominal –>mode
ordinal –> median
interval & ratio –> mean

Question 17

use the mode when

Answer 17

1. The variable is measured at the nominal level. 2. You want a quick and easy measure for ordinal and interval-ratio variables. 3. You want to report the most common score.

Question 18

use the median when

Answer 18

1. The variable is measured at the ordinal level. 2. A variables measured at the interval-ratio level has a highly skewed distribution. 3. You want to report the central score. The median always lies at the exact center of a distribution.

Question 19

use the mean when

Answer 19

1. The variable is measured at the interval-ratio level (except when the variable is highly skewed). 2. You want to report the typical score. The mean is “the fulcrum that exactly balances all of the scores.” 3. You anticipate additional statistical analysis.