Dispersion

Question 1

What is it?

Answer 1

Type of descriptive statistics that describes how spread out the data items are

Question 2

Range

Answer 2

Difference between the lowest and highest data value +1

ADVANTAGES:
-Identifies how spread out data is as it accounts for the end values of a data set

DISADVANTAGES:
-Values at either end of data may be extreme and so won’t actually represent the data
-Doesn’t take into account distribution as doesn’t indicate whether numbers are closely groups around the mean

Question 3

Standard Deviation

Answer 3

Shows the average distance of each number from the mean

ADVANTAGES:
-All values used so precise measurement of dispersion and can see how closely grouped around the mean (average) the values are
-Not as affected by extreme values

DISADVANTAGES:
-May hide extreme values as doesn’t just look at values at end of data set

STEPS:
1. Calculate mean
2. Subtract mean from each value in data set
3. Square the new values
4. Add them together
5. Subtract 1 from total number of values in data set
6. Divide total number of values by the sum of the values
7. Square root for the standard deviation