Measures of Dispersion

Question 1

What is measures of dispersion ?

Answer 1

A set of data can be described in terms of how dispersed or spread data items

Question 2

What is range?

Answer 2

The distance between top and bottom values in a set of data

Question 3

What should you add to the range?

Answer 3

+1

Question 4

How is the range calculated?

Answer 4

The difference between the top and bottom value +1

Question 5

What are the strengths of the range?

Answer 5

Identifies how spread out the data is because it accounts for the end values of the data set

Question 6

What are the weaknesses of the range?

Answer 6

It is affected by extreme values because values at highest and lowest points are used and these may not reflect the data set accurately
Fails to take into account the distribution of number meaning it does not indicate whether most numbers are closely grouped around the mean or spread evenly

Question 7

What is standard deviation?

Answer 7

Measures the spread of the set of numbers, in effect the average distance of each number from the mean

Question 8

How is the standard deviation calculated?

Answer 8

Calculate the mean of the values
Raw numbers - mean values
Square each number
Add together square numbers
Divide by amount of raw scores
Square number

Question 9

What are the strengths standard deviation?

Answer 9

Not affected by extreme values as it does not measure highest or lowest values
It is a precise measure of dispersion beachside all values are taken into account

Question 10

What are the weaknesses of standard deviation?

Answer 10

May hide characteristics such as extreme values