Student quiz scores will be higher if the instructor wears business clothes rather than casual clothes. Student Quiz Scores will be higher still if the instructor wears formal clothes rather than business clothes. See the lab handout for formulas for these measures if you are interested. The standard deviation is a little more work to calculate than the mean, but it is still fairly straight forward. First you have to calculate two other values.
Deviation is the distance of each measurement away from the mean.
If the mean were 10, and a measurement were 8, the deviation would be 2. So, variance is a measure of the variability of measurements around the mean. Standard deviation is simply the square root of the variance. It s kind of like correcting for having squared the deviations. Now we are able to use this information to ask whether the difference in two distributions is likely to have come about by chance or because the values from which they are taken really are different.