Question

Statistics P values --- probability P is observed to be 0,55. We're testing H0: P=0.5 against H1: P>0.5. What is the p-value for this test?
Answer is 0.16:
How to get there?

Answer 1

@mww and @Gokuporter

Answer 2

Your hypothesis test.
Null hypothesis. Probability is 50/50 (0.50)
Alternative hypothesis P > 0.5

You statistic for a proportion is then given by
\[z = \frac{ p - p_0 }{ \sqrt{\frac{ p(1-p) }{ n }} }\]

where p is the actual probability, p0 is the assumed probability according to the null hypothesis and n is the number of observations.

Plug these in, then use a set of z-tables to compute the corresponding p-value greater than the z-score obtained.

Answer 3

Thanks! I managed to get the answer in the end :)