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.
For the supporting workpack for this video visit biologybreakdo....
For more GCSE and A-Level content visit biologybreakdown.co.uk where you will find detailed workpacks with consolidation, knowledge recall and application questions and answers.
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[@BiologyBreakdownwithMrsH]

Please note 06:32 sum should be 12.1 not 10.411 - not sure how I went wrong as the final answer is correct! See below for instructions on how to use Casio fx-991EX for a calculator short cut

[@BiologyBreakdownwithMrsH]

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)

[@eduncan5392]

Excellent tutorial, and includes the use of a calculator! Thanks a lot :)

[@BiologyBreakdownwithMrsH]

Thank you! 😊

[@kasiafurczon4052]

That is great, just confused with one thing... why is -1.3 , 1.69 squared and not -1.69?

[@BiologyBreakdownwithMrsH]

It's a Maths thing, when you square a negative number it gets rid of the negative sign. Do it in your calculator and you will see. Have a chat with your maths teacher about why that happens, I just teach the maths needed for Biology. Hope this helps? 😊

[@kasiafurczon4052]

@@BiologyBreakdownwithMrsH That is great thank you !

[@dualgunz8699]

Thank you!!

[@BiologyBreakdownwithMrsH]

You are very welcome 😊

[@ise8882]

in a level psychology we also learn about standard deviation is this like the same x

[@BiologyBreakdownwithMrsH]

Hello Iseoluwa! Yes it is. You need to check with your teacher whether you need to use the standard deviation formula for a sample of the population (which will probably be the case). In maths they do standard deviation but with a whole population of data so the formula and setting on the calculator is slightly different. Your calculator may be different from mine so you may need a hand with working it out quickly on your own calculator 😊

[@ise8882]

@@BiologyBreakdownwithMrsH thank you Mrs H

[@فَذَكّر-س2م]

very useful! thank you

[@BiologyBreakdownwithMrsH]

Thank you for your lovely comment 😊