1What term refers to a a measure describing how spread out scores are? (Mean’s not enough)
Measure of Variability
2What measure of variability shows the difference between the highest value and the lowest value?
Range
3How is the range misleading?
Outliers can affect it
4What measure of variability shows the width of the middle 50% of the distribution, otherwise known as the difference between the 75th and 25th percentile?
Interquartile Range
5How do you find the position of Q1?
N x 0.25
6How do you find the position of Q3?
N x 0.75
7What kind of graph shows five key values, the min., Q1, the median, Q3, and the max.?
Box Plots
8What term refers to the difference between an individual score and the mean?
Deviance from the mean
9What’s the formula for deviance?
Y - Y-bar
10If deviations always sum to zero, what must be done?
They must be squared
11What term refers to the average of all squared deviations from the mean? (denoted s^2)
Variance
12What’s the formula for variance?
s^2 = sum of (Y * Y-bar)^2 /N - 1, where N refers to the total number of cases
13What’s a limitation of the variance?
Harder to interpret
14What term refers to the square root of the variance? (denoted s)
Standard deviation
15What’s the formula for standard deviation?
s = sqrt[s^2]
16If the standard deviation is zero, what does that tell you?
No variability
17If the standard deviation is small, what does that tell you?
Low variability
18If the standard deviation is large, what does that tell you?
High variability
19If your data is ordinal, which measure of variability is used?
Range and IQR
20If your data is interval-ratio and symmetrical, which measure of variability is used?
Variance and Standard Deviation
21If your data is interval-ratio and skewed, which measure of variability is used?
Range and IQR (SD skewed)