# Statistical significance

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I'm doing my EE in biology and I need to calculate the significance of my results. I tried using the 2 sample t-test, but I have no idea of what I'm doing!

Anybody got any experience in this?

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Well, It's kind of difficult knowing which values to list.

I have values of initial weight and final weight of my samples, and also their percentage weight loss.

In my investigation I have two groups, and the null hypothesis is that they have no significant differences in weight loss at different temperatures.

Do you need the average value of percentage weight loss for each temperature?

I have roughly nine samples at each temperature in both groups. That is, 36 samples (initial weight, final weight, percentage weight loss) for each group.

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Oh, my. I don't know if that was understandable.

It's quite difficult trying to explain something you've gotta that far into.

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Since you are testing the difference of two samples in weight loss in different temperatures you will definitely need the mean of percentage loss for both groups in order to do the t-test. Then you find the standard deviation for the groups. Having these values it is not hard to calculate for the t value using the following formula: http://www.nursingplanet.com/biostatistics/t-test-formula.jpg

Once you have the t value you calculate the degrees of freedom (total number of samples, thus 18 for yours minus 2). Then use the 0.05 column of the table for critical values of t and you will see a value (2.12). If your t is below the critical value, i.e. 2.12 the results are not significantly different and therefore you accept your null hypothesis. If your t is above 2.12, the results are significantly different and you reject the null hypothesis.

If you need further clarification let me know! =) Good luck!

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