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Thread: Indepedent or paired t-test?

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    Exclamation Indepedent or paired t-test?




    If you are comparing the number of barnacles (% cover) on two different sides of rock which test would you take?

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    Re: Indepedent or paired t-test?

    Both measures taken at the same time?


    How do you decide a side of a rock?
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    Re: Indepedent or paired t-test?

    Yes at same time.

    Comparing greater exposure to sea i.e. cliff facing and sea facing.

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    Re: Indepedent or paired t-test?

    An easy solution does not jump out at me. You have a relationship and the sides are not independent.


    Is the surface area different on each side, so you need to calculate the rate of barnacles, and are they the same size on each side? So small barneys don't prefer to hang out on the cliff side?


    Can you find any other comparable studies and see what they used. Ecological data can be difficult, since many things cannot be controlled and variable may be inter-related .
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    Re: Indepedent or paired t-test?

    Would this be a single rock or multiple rocks? If multiple rocks, the samples from each rock would be paired by unique rock.

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    Re: Indepedent or paired t-test?


    If it was multiple rock you may also be able to treat it as a binary variable. So Rock A had 60% barneys on the front, etc. and you could put confidence intervals on it or compare the value to 50% (e.g., no difference). Something like this perhaps.
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