Chapter 4: Measures of Central Tendency Flashcards Preview

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Flashcards in Chapter 4: Measures of Central Tendency Deck (17):
0

Mean?

arithmetic average
x-bar
sum of the set of scores divided by the number of scores summed...
X= ΣΧ/Ν

1

Sample Mean?

X bar = x1+x2+x3.....XN/N

2

Population mean?

mew= X1+x2+x3....XN/n

3

Mean Properties?

sensitive to values of all scores in distribution..
sum of the deviations about the mean = zero
if you subtract the mean from each score and than sum the values...it will equal zero...

4

Outliers?

extreme points that shift the mean.....

5

Σ(Χ-χ)2 = sum of squared deviation..

basically it will be smaller than other value substituted in instead of the mean
the further x bar gets from the actual mean the higher the deviation is

6

Mean is the least or most subjective to variability.

Mean is least!
Mean

7

Overal Mean?

mean for many samples...

(mean of group 1)(number of scores) +.........
divided by total number of scores from all groups

8

Median

point with which fifty percent of scores fall in.
Mdn = mean
less sensitive to extreme scores..
to calc for it just do P50

9

Mode?

most frequent score in distribution
no math
unimodal means only one
bimodal : two that are equally frequent

10

Symmertry?

bell shaped curve: middle = median, mode, mean!
in positive skew ...mean is shifted near the right
negative skew...mean shifts left....

11

Mean : scale ?
Mode : scale?
Median: scale?

mean: ratio or interval
mode: nominal
median: ordinal

12

Mean of frequency distribution formula?

Σf(MP)\N
Mp= midpoint of URL and LRL
F = frequency
Sum all midpoints mult by their f and divide by total number of scores

13

Range?

Highest URL- lowest LRL

14

Deviation scores

How far each raw score is from mean

15

Variance

Σ(x-Χ)/Ν

16

Standard deviation ?

Square root of Σ(χ-Χ)2/Ν-1
N-1 makes or unbiased
When dealing with samples!