Chapter 3 Flashcards
(16 cards)
1
Q
central tendency
A
- statistical measure.
- purpose is to find the single score that best represents the entire group.
2
Q
central tendency measures
A
- mean (average).
- median (middle).
- mode (most common).
3
Q
mean
A
- sum of all scores divided by number of scores in the data.
- population = sum of x divided by N.
- sample = sum of x divided by n.
4
Q
computing mean from frequency distribution tables
A
M = sum of fx divided n
5
Q
weighted mean
A
M = (sum of x1 + sum of x2) / (n1 + n2)
6
Q
mean is sensitive to…
A
- changes in scores.
- changing, discarding, or adding scores will usually change the value of the mean.
- adding/subtracting/multiplying/dividing by a constant changes the mean by that constant.
- two scores that balance each other out (M-1, M+1) results in no change in mean.
7
Q
median
A
- midpoint of scores in a distribution when listed in order from smallest to largest.
- ordinal, interval, or ratio scales.
- direct split in half.
8
Q
mean is defined by…
A
- distances.
9
Q
median is defined by …
A
- number of scores.
10
Q
mode
A
- score or category with greatest frequency of any score.
- any scale of measurement.
- corresponds to an actual score.
- can have more than one mode/no mode.
11
Q
symmetrical distributions
A
- mean and median are equal.
- one mode (which is the same as mean and median).
12
Q
bimodal
A
- two modes.
13
Q
rectangular
A
- no mode.
14
Q
skewed distributions
A
- mean is toward tail.
- median is toward tail but not as far, closer to the mode.
- mode at the peak.
15
Q
mean - median > 0
A
positive skew.
16
Q
mean - median < 0
A
negative skew.
