One can have a difficult time comparing two data sets without
converting the data to a simpler form. We can compare these two sets of data
by computing an average, or *mean* ().
Furthermore, we seldom represent a mean value without an accompanying measure
of random error, usually the *sample standard
deviation* (*s*). In a table or in text we write these quantities
as* * ± *s*.

What were the mean heights of the two species 3 months after germination, including standard deviations, both quantities rounded to reflect the precision of the actual measurements? First,paste or type the data into an Excel spreadsheet. Now select a blank cell, choose Insert/Function.../Statistical, select AVERAGE, select your data and hit OK. Do likewise for the standard deviation, but select STDEV instead.

species | mean (µ) |
std dev (s) |
---|---|---|

Quercus rubra |
||

Quercus alba |