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Urgent help needed,please help.

I will be doing Biology A2 ISA ,the board is AQA. I have a very urgent question,please someone look into this matter. The title of my ISA is "You will investigate the effect of oxygen on the growth of yeast cells. In addition you will also need to understand the folloing topics. Popluations and competitions." Now as per rule of AQA board there is statistical test paper and then a written paper. We get marked for choosing the best statistical test for analysing our results out of a choice of three,which is Chi-squared,standard error and 95% confidence limits and spearman rank correlation test. For this set of investigation which one is the best statistical test to choose and why do you choose that test? And also if one would be using standard error and 95% confidence limit just as an example for to analyse their data. We first calculate the standard deviation,then standard error for our sample and then for our next sample given to us in exam paper. But then we work out 95% confidence limit for our sample and the other sample. But how do we give our final statistical value. Is our final value which will be quoted in the exam be the sum of the two standard errors. Please help!!!
Reply 1
Avatar for Jacko2667
Jacko2667
1
The final statistical value will be the MEAN/AVERAGE of your orginal values in your table +and- 1.96 TIMES your standard error.

for example. Say i had the results from my experiment which were- 36, 37, 40, 45 and 42.

The MEAN/AVERAGE of this would be 34.

Then you work out the standard error (which im not going to, but lets just say its 3.2.)

Times this standard error by 1.96 which equals 6.27.


Now you take away and add 6.27 from 34 which equals-

27.73 and 40.27. These are you standard error bars or ranges.


Reapeat this for you control experimetnal results and if the standard error bars overlap. I.E- The control experiments error bars were 29.55 and 37.22 then your results are NOT STATISCALLY SIGINFICANT.


Hope that helps (and the statisics paper is on standard error!!!) :biggrin:


Once you have worked both the standard error bars for your experiment and your control- that is your final values.
(edited 13 years ago)
Have you done the ISA paper yet?
Reply 3
Avatar for Jacko2667
Jacko2667
1
Original post by CHELSEA123456
Have you done the ISA paper yet?


Not the written one, only the statistics paper. Sorry bud x
Reply 4
Avatar for beccyboo
beccyboo
i have the written exam tomorrow am so stuck!! do you know what will be on the seocnd part of the paper? like populations? or respiration etc????

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