Variability

Question 1

Variability

Answer 1

the scatter of scores in a distribution
- describes the spread of data

Question 2

What is deviance (d)?

Answer 2

The distance of each raw score from the mean

Question 3

Total deviance

Answer 3

the sum of all deviances = 0

Question 4

Sum of squares (SS)

Answer 4

the sum of squared deviations (adding up all squared deviations)
Value depends on number of scores in data

Question 5

Variance

Answer 5

Average distance between the mean and the data points
samples = statistics/estimates
populations = parameters

Question 6

Standard deviation

Answer 6

The square root of the variance
- should be used to summarize variability in a set of data
- Easiest measure of variability to interpret

Question 7

Coefficient of variation

Answer 7

Allows us to compare two standard deviations

Question 8

If N is large…

Answer 8

5 or 6 standard deviations within a range of a data set
- this doesn’t apply with a small N and if the data is skewed
*This is important when identifying outliers and determining if two groups are actually different