Ch03 Central Tendency

Question 0

Mean

Answer 0

arithmetic average - sum of the scores divided by the number of scores

every score has equal contribution

mean for population = μ

mean for sample = M or X (with a bar on top)

Question 1

Central Tendency

Answer 1

statistical measure to determine a single score that defines the center of a distribution

find most typical / representative of the group

Question 2

Weighted Mean

Answer 2

First sample has M=6 and contributes 12 / 20 scores, second has M=7 and contributed 8 / 20 scores

weighted mean = (12 / 20) * 6 + (8 / 20) * 7

Question 3

Median

Answer 3

arrange scores in order, take middle one

Question 4

Mode

Answer 4

score or category with greatest frequency

only measure of central tendency that can be used with data from a nominal scale of measurement

(also only to correspond with actual score in data)

Question 5

Selecting Measure of Central Tendency

Answer 5

typically mean (defined by distance)

median: extreme values, skewed distributions, undetermined values, open-ended distributions, and with ordinal scales (since defined by direction)
mode: discrete values (both are whole), describing shape (knowing where peaks are helps), and with nominal scales (since no measure of distance or direction)

Question 6

Know where mode, median, and mean are in symmetrical and skewed graphs

Answer 6

Positively skewed: mode at peak, then median between mode and mean on right