Measuring Spread

Question 1

How can the range be calculated?

Answer 1

largest value - smallest value

Question 2

How can the interquartile range be calculated?

Answer 2

interquartile range = upper quartile - lower quartile.

Question 3

How can the upper quartile be found?

Answer 3

= (n+1) / 4 x 3

Question 4

How can the lower quartile be found?

Answer 4

= (n + 1) / 4

Question 5

What are the advantages of using the interquartile range?

Answer 5

1. It is not extorted by extreme values.

2. It excludes outliers.

Question 6

What are the disadvantages of using the interquartile range?

Answer 6

1. It doesn’t use all the values; cutting off 50% of the data.
2. It can exclude central values.

Question 7

What is a decile?

Answer 7

A tenth.

Question 8

What does each section of a box plot represent?

Answer 8

25% of the data.

Question 9

What is negative skew in a box plot?

Answer 9

When the data is spread out more at the lower end and clustered together more at the higher end.

Question 10

What is positive skew in a box plot?

Answer 10

When the data is spread out more at the higher end and clustered together more at the lower end.

Question 11

What are outliers?

Answer 11

Outliers are values more than 1.5 times the interquartile range away from the nearest quartile.