Measures of Central Tendency

Question 1

Population Mean

Answer 1

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

Population Mean is the mean of all the values in the population.

Question 2

Sample Mean

Answer 2

X bar = x1+x2+x3…..Xn/n

The mean of sample values collected. If the sample is random and sample size is large then the sample mean would be a good approximation of the population mean.

Question 3

Mean Properties

Answer 3

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…

Question 4

Outliers

Answer 4

Extreme points that shift the mean

Question 5

Median

Answer 5

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

Question 6

Mode

Answer 6

most frequent score in distribution

Question 7

Symmetry

Answer 7

In a bell shaped curve:
The median and mean have the same value

in positive skew, tail is longer on the right, mean is shifted more towards the right

In negative skew, tail is longer on the left, mean is shifted more towards the left

Question 8

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

Answer 8

Mean: Interval or ratio
Mode: Nominal
Median: Ordinal

Question 9

Deviation scores

Answer 9

How far is score is from the mean

Question 10

Variance

Answer 10

Σ(x_i-Χ_bar)^2/N for population variance
Σ(x_i-Χ_bar)^2/n-1 for sample variance

Measure of the spread between numbers in a dataset

Question 11

Standard deviation

Answer 11

A measure of the amount of variation or dispersion of a set of values. Is the square root of the population/sample var