mayfly nymph reproduction rate

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nicola
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mayfly nymph reproduction rate

Post by nicola » Sat Feb 12, 2005 9:59 am

my hypothesis is there are greater no of mayfly nymphs at areas with a fast flow rate (site A) than at an area (site B) at a slower one. What stats test do i do??Plz help!thankzz

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mith
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Post by mith » Sat Feb 12, 2005 9:09 pm

Does your teacher ask you to do actual experiments or to use available texts?
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nicola
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Biology coursework help needed

Post by nicola » Sun Feb 13, 2005 11:17 am

We have to do the experiment!So basicaly I have one site of fast flowing water and 6 samples and another site of slower flow rate with 6 samples. Does that make sense?What stats test do I use?Thankz

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Post by RobJim » Sun Feb 13, 2005 2:46 pm

This sounds like a really hard experiment. This website says that the mayfly nymphs live in little burrows, under rocks, and among plants:

http://www.bugsurvey.nsw.gov.au/html/popups/bpedia_02_vsens_ma-ny-a.html

This means that you can't just get some water and then count the nymphs in it. I don't know how you'd go about determining what the concentration of nymphs is at a certain place.

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Post by DevGrp » Mon Feb 14, 2005 1:27 pm

So I would sample a series of fast and slow flow areas for a set time and then compare the numbers from the two groups. I'm not sure HOW you would count them but...

As you only have two different data sets to compare then you want to do a T test.

If you had condition A(fast), B(slow) and C (intermediate) then you might want toconsider an ANOVA, which is better than doing lots of individual T tests.


T test assumes that your samples are normally distrubuted, If they aren't then you would have to do a Mann Whitney test.

You can do a t test using Excel and the Ttest fucntion command (see the help)


hope this answers your question?

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mith
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Post by mith » Mon Feb 14, 2005 8:16 pm

How long do you have to do this experiment?
Living one day at a time;
Enjoying one moment at a time;
Accepting hardships as the pathway to peace;
~Niebuhr

nicola
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Biology coursework

Post by nicola » Wed Feb 16, 2005 10:54 am

I have a week to do my whole coursework!Thankz so much 4 all of ur help. I need to do a Mann Whitney U test. I was wondering what limitations would I need to talk about when doing this kind of experiment?That bit is realy hard! Thankz alot!

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