Standard Deviation - A Level Biology

Calculating Standard Deviation is a required skill in A Level Biology. It is also an integral part of some statistical tests, including the Student's t-tests. This goes through:
what standard deviation is
how to work out the values and how to substitute into the formula
a 'shortcut' method to calculate standard deviation using the STAT mode on your calculator (shown using Casio fx 83GT. If you have a different calculator try the method for Casio fx-991EX by following the instructions below)
how to plot and interpret error bars

If you have a Casio fx-991EX - follow these instructions.
Step 1 - Go to menu – choose 6 and then 1
Step 2 - add values to table
Step 3 - Press ‘AC’
Step 4 – Press ‘OPTN’
Step 5 – Press 2
Step 6 – scroll down to find sx

For fx 83GT follow instructions in the video. If neither method works for your calculator you will need to look up your model maybe ask your Maths teacher but remember you need to use sx because in Biology we only use samples of data.

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