 Topic: Simply way to calcuatle p value ? (Read 2173 times)
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## Simply way to calcuatle p value ? ##### 2019-02-21 15:06:45
i undersand the improtna of p value and waht it represent. im just not good at getting the math right and everything i look up has it way overcomplicated for my little needs
So anyone that can help my with a simple way to calcuatle it for my A/B situations ?

In my test the issue is either True or false ( kinde like in ABX testing)
I want to  calcaulte thd P value for the results being true

aka let say 12 trials
trial 1  True
trial 1  Trues
trial 1  Trues
trial 1  False
trial 1  Trues
trial 1  False
trial 1  TRues
trial 1  TRues
trial 1  TRues
trial 1  TRues
trial 1  TRues
trial 1  TRues

aka 12 trials. ( 10 Trues. 2 False)

What is the simplest way to calculate the p value here? cutting out anything related to test done with other paramets

Sven Bent - Denmark

## Re: Simply way to calcuatle p value ? ##### Reply #1 – 2019-02-22 09:17:25
The "simplest way" is, arguably, to enter the figures into an online calculator: https://www.google.com/search?q=binomial+test+calculator
The null hypothesis of wild guessing would be a probability = 1/2 each time, since you have two alternatives A and B.  What you are looking for, is the chance of getting "such a wild result" as 10 or more, if the null hypothesis is true.

If you want to do it by hand: Then https://en.wikipedia.org/wiki/Binomial_distribution#Cumulative_distribution_function .
Rather than calculating up to 10, you can calculate "from 10 and up": since probabilities are 1/2 The chance of getting 10 or 11 or 12, equals the chance of getting 2 or 1 or 0. The probability of 1/2 simplifies p^k(1-p)^{n-k} to 1/2^n.

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