# Statistical tests Watch

1. Hi

I'm investigating the effect of CO2 on the rate of photosynthesis for my biology coursework. What i've done is add increasing amounts of sodium hydrogencarbonate in order to vary the amount of O2 gas produced, and I found that there's a positive correlation between the two.

Howeverrrr, I have absolutely no idea which statistical test I am able to use... I tried using Spearman's rank, but when I ranked O2 + hydrogencarbonate, they were ranked equally, which means that when they're subtracted from one another, I get 0.

Thank you!
2. (Original post by TheStudent.)
Hi

I'm investigating the effect of CO2 on the rate of photosynthesis for my biology coursework. What i've done is add increasing amounts of sodium hydrogencarbonate in order to vary the amount of O2 gas produced, and I found that there's a positive correlation between the two.

Howeverrrr, I have absolutely no idea which statistical test I am able to use... I tried using Spearman's rank, but when I ranked O2 + hydrogencarbonate, they were ranked equally, which means that when they're subtracted from one another, I get 0.

Thank you!
If you used at least 2 different concentrations of NaHCO3, I'd go for Standard Error and 95% Confidence Limits, as they measure the difference between the mean values of each concentration.

However, you'd have to do quite a lot of repeats in order to get a precise answer .
3. (Original post by thegodofgod)
If you used at least 2 different concentrations of NaHCO3, I'd go for Standard Error and 95% Confidence Limits, as they measure the difference between the mean values of each concentration.

However, you'd have to do quite a lot of repeats in order to get a precise answer .
So basically i'm screwed

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