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IB BIology Extended Essay - Data Analysis Help

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Hi all

I just need some general ideas on how to process my data results I collected for my experiment

My RQ is: How will different concentrations of simulated acid precipitation effect the flower bud count on [i]Lobularia maritima[/i]?

I have my results and I'm have about 2,000 words left for my essay.

The acid precipitation is simulated using nitric acid. The different concentrations are calculated by pH level of the precipitation. Here's some background information, normal precipitation has a pH of 5.6 and anything lower is considered to be acidic. My five groups are pH 2.7, 3.3, 3.9, 4.5, 5.1 and control group is pH 7.0 (distilled water). I have 20 samples for each group examined (it used to be thirty, but some of them died), controlled all variables within my limitations.

For my results, as the pH level gets closer to 7.0, there are more flower buds produced

my problem right now is, I don't know what to do with the data, I was thinking about standard deviation, but I got confused at what it actually does...

My first draft is due in 2 weeks...

Please and thank you

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Well, Standard Deviation is a measure of the variability of data (definition). It is used when you have to compare two means (the different samples) so as to see whether if the mean is representative of the whole set of data. For instance:
I'll invent an example with random measures.
Sample 1: 5cm, 7cm, 8cm, 9cm, 11cm. Mean = 8cm.
Sample 2: 1cm, 3cm, 9cm, 12cm, 15cm. Mean = 8cm.
As you can see, both samples have the same mean (8cm) but in sample 2 the values are not clustered around the mean. If you calculated the Standard Deviation for each of the samples you would get a low SD for Sample 1 (meaning that the values are quite close to the mean) and a high value for sample 2. After calculating the SD you can use the t-test to assess whether the difference between these two means is significant or not. Have you discussed your Research Question with the person that is monitoring your EE? I think it is a bit broad. I would change it to: "Does an acidic p.H affect the flower bud count in Lobularia maritima" or something of the sort. Once you have the SD of each of the samples (the ones you are comparing) these would be the control and the samples using different p.Hs you can use the t-test to compare these means. I hope my answer clarifies a bit your doubt. I'll keep in touch.

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