Statistics, Day 4

On Friday, we went further into the concept of mean absolute deviation. We looked at two sets of grades for students that have the same average or mean (75%) and the same range (from 60% to 90%). However, they were very different students. One had grades more balanced out in the span from 60 to 90; while the other had grades that either were high 80s to 90 or were low 60s. I used these sets to introduce the statistic that measures the deviation away from the mean, or a set of data's variability. To calculate the mean absolute deviation:

1. Calculate the mean.
2. Find the distance from every number in the set away from the mean. These are the deviations.
3. Find the average of all deviations by adding them together and dividing by the number of data in the set. This is the mean absolute deviation(MAD).

The higher the value of the MAD, the less consistent the data are around the mean. Or, the more variability the data has away from the mean.

Homework: Page 365; #9 - 14 and 17 c & d

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