In: Statistics and Probability
We had an example in class about using a sign test. We are supposed to find the b value by using the binomial table. b(alpha,n,1/2) which for this problem equals b(.05,10,1/2). When you use the binomial table, the b(.05,10,1/2) = 8. How do you use the binomial table to get 8 for the b value?
We are asked to find number of success x , such that the the probability of success on single trial p is 1/2 or 0.5 and number of trials n = 10 and the binomial probability for that x is 0.05
So we look under the region for n = 10 , across p = 0.50 and we have to find x such that binomial probability is 0.05 or nearest.
0.05 is not available in the column p = 0.05 under the region of n = 10, but its nearest number 0.0439 is available and it belongs to the row x = 8
Therefore we got x = 8 such that binomial probability is approximately 0.05 for n =10 and p = 0.5
If you have to cross check, you can find the binomial probability for x = 8 , n =10 and p = 0.5 using excel fuction =BINOMDIST( x,n,p,cumulative ) , plug the values accordingly and for cumulative plug "FALSE"
=BINOMDIST( 8,10,0.5,FALSE ) = 0.044