"Student's" t Test – Interactive tutorial



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