8.3 Measures of spread

• Wiskunde
• Middelbare school
• vwo
• Leerjaar 3

If the mean is the same

but you can see that there are clear differences in the values in the list you can look at the deviation from the mean

and 

the mean deviation from the mean

If the mean deviation from the mean is low 

then the numbers are all close to the mean

If the mean deviation from the mean id high 

then the numbers are more spread out from the mean

Range

In statistics, a small spread of data is when the data is close to the mean.

A measure of spread is the range.

The range is the difference between the highest and the lowest vale.

Range = Highest - Lowest

Lower quartile 

This is the median of the lowest (first)half of the data.

Q​1​​

Upper quartile 

This is the median of the upper (second) half of the data.

Q​3​​

Interquartile range

This is the difference between the lower and upper quartiles.

Interquartile range = 

This is also a measure of spread, just as the range is.

Q​3​​−Q​1​​

Homework

Paragraph 8.3 pages 18 t/m 20

Exercises 17 t/m 20