# Statistical test for A2 biology

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Thread starter 18 years ago
#1
I'm doing ok at my project but need a stat. test asap!

The title is "How the growth of yeast is effected by the carbon source used" essentially the results are in CM3 and i need to prove that glucose is the fastest substrate whereas lactose is the slowest, i have 5 repeats and a mean, and cumulative number but i don't have enough data for a t-test (or do i?)

Did a poisson test to prove that 5 would give me an appropiate % of cumulative prob.

And have attempted the following
• Spearmans rank correlation
• regression analysis (prob wrong)
• wilcoxon matched pairs test
• not enough data for Mann-Whitney u
• Students t-test

Some of these may have come up with the right answer though i'm so bad at maths (8% on S1!)

Anyhelp grealtly apprechiated!

Petree!
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18 years ago
#2
(Original post by Petree)
I'm doing ok at my project but need a stat. test asap!

The title is "How the growth of yeast is effected by the carbon source used" essentially the results are in CM3 and i need to prove that glucose is the fastest substrate whereas lactose is the slowest, i have 5 repeats and a mean, and cumulative number but i don't have enough data for a t-test (or do i?)

And have attempted the following
• Spearmans rank correlation
• regression analysis (prob wrong)
• wilcoxon matched pairs test
• not enough data for Mann-Whitney u
• Students t-test

I did a similar experiment at A2 - looking at the rate of respiration in yeast with glucose, sucrose and lactose. I managed to do a Mann-Whitney U test though....? And a chi-squared test. Have you spoken to your teachers about it? Ours gave us the stats tables and formulae etc.

Hope that's of some help.
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Thread starter 18 years ago
#3
Can't see how i would do this, pls help!

I have the following data

Sucrose (5 min between figure)
Mean 1.52 3.38 5.86 6.18 4.98 4.34 1.68

Glucose
Mean 2.62 7.86 6.68 6.50 2.86 0.64 0.20

Do i need the total mean i.e. all of these divided by 7, or am i missing something?

everytime i try and talk to my techer he starts going on about how he can't help or marks will have to be deducted! which i don't even begin to understand since i could ring up GSK or something and ask them but can't ask him?!?

Would mann-whitney provide the right answer?

http://eatworms.swmed.edu/~leon/stats/utest.cgi
U Test Results
n1 n2 U P (two-tailed) P (one-tailed)
7 7 25 1 0.5
normal approx
z = 0.0638877 0.94906* 0.47453*
*These values are approximate.

The two samples are not significantly different (P >= 0.05, two-tailed test).

this helps (the wrong way but) since it gives me the 'are they different answer', does anyone know how much (ahem) fakery i will need to ensure it fits my hypothesis, the results are different but must not be enough for this.
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