You’re on the right track!

Do you remember how to calculate a standard deviation (SD)? If not, there’s a quick review below.

Of course, the easy way to do this is to use your calculator or a spreadsheet, assuming that’s ok with your instructor. However, it is important to ** understand what the standard deviation is doing**. Basically, it accounts for

**. For example, the smallest fish in the Fish-2-Whale group gained 212g, or 55 grams less than the average while the largest fish gained 324g, or 57 grams more than the average. These are the “deviations” from average.**

*how far each data point is from the group average*It would be convenient if we could just average the deviations, but unfortunately it’s not quite that simple. Instead, we ** square each deviation (partly to get rid of the plus or minus signs), average the squares (except that we divide by n-1 rather than n), and then take the square root of that number**. (So, in short form: square, average, square-root). The result of that is the standard deviation. The formula for the sample standard deviation looks scary, but it’s really just the above steps: