CT4 April 2016 question 4 i

[Priyanka Malhotra]

Hi, could someone please help me understand how does having 17 positive signs wont reject the test as at 17 the p value is 2.2% and p value at 16 is 5.4%, given this is a 95% significance level, I think it should reject the test at 17 positive signs.. thanks in advance!

 

[Andrew Martin]

Hello

At 16 the p-value is P(X > = 16) * 2 = 0.11476 * 2 = 22.95%
At 17 the p-value is P(X >= 17) * 2 = 0.05388 * 2 = 10.78%
At 18 the p-value is P(X >= 18) * 2 = 0.02164 * 2 = 4.33%

So we would reject at 18 but not at 17. Therefore, we must have 17 positive signs.

Hope this helps!

Andy