Spread of a data set – standard deviation & variance  Measures of Dispersion
Spread of a data set – standard deviation & variance
Basic concepts:
 Center of a data set: mean, median, mode
Lessons
Notes:
• Standard Deviation measures the average distance data values are from the mean.
note:
When the values in a data set are tightly bunched together, the standard deviation will be small.
When the values in a data set are spread apart, the standard deviation will be relatively large.
$variance=\sigma^2$

1.
Determining Population Standard Deviation VS. Sample Standard Deviation
The heights of students (in cm) in a class are: {148, 156, 160, 164, 164, 167, 171, 176, 180, 194}