[R] binom.test & p-value

[Rui Barradas]

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Rui Barradas

Às 19:19 de 03/04/2022, Rui Barradas escreveu:
> Hello,
> 
> Can you post your computations? Assuming a two-sided test, mine are
> 
> 
> x <- 6
> n <- 26
> p <- 0.1
> 
> cmb <- sapply(x:n, \(i) choose(n, i))
> sum(cmb * p^(x:n) * (1 - p)^(n - (x:n)))
> #[1] 0.03985931
> 
> binom.test(x=6, n=26, p=0.1)$p.value
> #[1] 0.03985931
> 
> 
> The result are equal to one another.
> 
> Às 19:00 de 03/04/2022, Sigbert Klinke escreveu:
>> Hi,
>>
>> for the specific example binom.test(x=6, n=26, p=0.1) I get as p-value 
>> 0.03986. The default approach to decide whether I can reject the null 
>> or or not is to compare the p-value with the given significance level. 
>> Using a significance level of 0.05 this will lead to reject the null 
>> hypothesis.
>>
>> However, computing things by hand it turned out that the critical 
>> values are 0 and 6. Since the test statistic is also 6 I can not 
>> reject the null hypothesis.
>>
>> I found the discussion under 
>> https://stat.ethz.ch/pipermail/r-help/2009-February/380341.html and I 
>> understand that a p-value is not well defined if we have a asymmmetric 
>> (discrete) distribution under the null.
>>
>> At least I would have expected some hint in the documentation for 
>> binom.test.
>>
>> Sigbert
>>
> 
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