dispersion

Question 1

range

Answer 1

difference between heighest and lowest scores in data set

Question 2

range +/-

Answer 2

+ simple
- affected by outliers
- only tells minimum and maximum

Question 3

interquartile range (IQR)

Answer 3

cuts off top and bottom 25% of scores, calculate range of middle 50%

Question 4

interquartile range (IQR) +/-

Answer 4

+ robust to outliers

Question 5

standard deviation

definition

Answer 5

measure for the spread of scores

Question 6

what does a low SD mean

Answer 6

data clustered around the mean

Question 7

what does a high SD mean

Answer 7

data is spread out

Question 8

when to use SD

Answer 8

when you have interval or ratio data that has no outliers

Question 9

how to calculate SD

Answer 9

1) work out the mean
2) calculate the differences between the mean and each data value then square them
3) add all squared differences up
4) divide by number of data units- 1 and sqaure root the result

Question 10

if the SD is high what does that mean for the normal distribution

Answer 10

wide