Recent content by obh

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    Clarification in statistical test

    Dason? :)
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    Binomial exact test - calculate p-value of two tailed test

    Hi Greta, Thanks for looking. Sorry I was confused I wrote p(x=X): x-variable, X value ...but it should be as you wrote. :( You missed the p, it is 0.25: > dbinom(x = 1, size = 8, prob=0.25) [1] 0.2669678 Sorry: "<=" means "less or equal to", ≤ . I didn't write any arrows. I updated all...
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    Binomial exact test - calculate p-value of two tailed test

    Do you have any idea Greta?
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    Non uniform sampling evaluation

    What do you mean?
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    Clarification in statistical test

    Yes that's what I meant I run a special case to feel the statistics. Is the "reasonably symmetrical" requirement for t-test also required when n>=30? Do you know any example of "badly behaved of a distribution" in R?
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    Clarification in statistical test

    What is the code tag? ~~code ~~ Any way, my conclusion from the simulation is that even for a non symmetrical distribution t test will do a good job. In this specific case example from around n=20. (I know the general thumb rule is say 30). Is this correct conclusion from this simulation?
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    Clarification in statistical test

    Okay, I fall for it again :) From some reason ... the website doesn't like the [ i ] and remove it from the code I paste :( I will update the code to [ i ] with spaces :) But the [j] works fine
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    Clarification in statistical test

    Hi Dason, I used the following code, I added normal distribution and colors and increased reps. df <- 4 # degree of freedom reps <- 800000 # number of simulations per one sample size sample_size=c(2,4,6,8,10,15,20,25,30,35,40) # sample size mean_pvalues <- numeric(length(sample_size))...
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    Clarification in statistical test

    Hi Karabiner Correct, but I may rephrase it in another way: The t-test uses t distribution. t-distribution assume normal data (uses instead of z when you don't know the population) Due to central limit theorem usually, when the sample size is large enough the distribution is approximately...
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    Clarification in statistical test

    Hi Alison and Kat, The Mann-Whitney U test compares only 2 groups. the Kruskal-Wallace is the equivalent non-parametric test to the one way above assuming H0 the rank of all groups is equal. So it is a good suggestion :) If you want to compare each pair (ab, ac, cb) then you must use a lower...
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    How to consider false positive rate when there is only one true positive?

    What is the meaning of "have X% probability of predicting the true causal gene in the top 10% of the ranked genes"? Is the false positive rate depends on the true positive rate? if yes how?
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    Comparing two samples with not independent observations within each one

    The volume 1 segment ago and 2 segments ago (or more) may also influence the heartbeat. Maybe check for "time series"?
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    Binomial exact test - calculate p-value of two tailed test

    I tried to understand how to calculate the two tails p-value of the binomial exact test (using the discrete binomial distribution). And why? I read there are 2 methods but could understand only one. I found that R calculates base on the density value if x is the actual value and x' is the...
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    Help with stats work

    Hi Dan, When you use sample data and you try to get conclusions from the sample to the population, then you may say that the results are significant if the behavior of the samples represents the populations. I have a feeling that you have the population data? or do you want to check if the...
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    Wilcoxon rank-sum test report results when Mdns are the same

    Actually, after reading the Wikipedia Wilcoxon sign rank page, it is a good page :)