Loading...
Reload document 
Open in new tab 2_3MeasuresOfSpread.notebook
April 29, 2013
Measures of Spread
RANGE = the difference between the maximum value and the minimum value
QUARTILE = divides a data set into four equal parts
Q1 is the first quartile (25%)
Q2 is the second quartile (50%) (this is the middle value in an ordered list… does this sound familiar?)
Q3 is the third quartile (75%)
INTERQUARTILE RANGE = Q3 Q1
VARIANCE = a measure of dispersion that is found by averaging the squares
of the deviation of each piece of data
STANDARD DEVIATION = another measure of dispersion = square root of the variance
1
2_3MeasuresOfSpread.notebook
April 29, 2013
Why do we take the average of the squares of the differences between each data point and the mean?
(from Math is Fun website)
variance
standard
deviation
2
2_3MeasuresOfSpread.notebook
April 29, 2013
Example:
(mean, median or mode??)
“consistency” can be measured with the standard deviation
Felix
Melanie
3
2_3MeasuresOfSpread.notebook
April 29, 2013
When viewing data in a frequency chart, remember to consider the frequency in your calculations!
Example:
4
2_3MeasuresOfSpread.notebook
April 29, 2013
Practice: p168169 #1, 2, 3, 5, 6, 10
5