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Thread: Comparison of two variables from one sample set

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    Comparison of two variables from one sample set




    I have collected two measurements from a set of 100 tumour biopsies. One measurement is the percentage mutant allele of a particular mutation. The other measurement is the percentage of tumour cells present in the biopsy. The data in neither set is normally distributed. Our research question is: is percentage mutant allele related to the percentage of tumour cells present in a biopsy?

    I use R for statistical analysis.

    Does anyone have an opinion on the best analysis method for this? I’m thinking of using Spearman’s rank.

    Thank you.

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    Re: Comparison of two variables from one sample set

    Percentages follow a binomial distribution, unless large enough to fit the Normal approximation.

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    Re: Comparison of two variables from one sample set


    hi,
    I would try to look at a scatterplot - percentage mutants vs. percentage tumor cells. If there is a link you should be able to see some pattern.

    After that, I would try a simple regression and check the residuals. If the residuals are normal,mthe model should be more or less ok. If not, the pattern of the residuals should provide some clues as to how to proceed.

    regards

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