syntax question

[Alex Field]

Hi, I have a tech question that I'm hoping someone can help me with. The question is: what STATA syntax would I use to answer the following?

What is the probability that 20 people out of 100 that I interview at random will have condition X? From previous research I know that an 40% of the population suffer with condition X.

Thanks

[Carlo Lazzaro]

Alex:
welcome to the list.
Your question sounds not that clear to me: the probability of what you're after is 20% (or 0.20, that is 20/100: this proportion is the estimate of the probability)
If this were the case, Stata (not STATA, please) syntax is as follows:

display 20/100

.

However, if your query is differet from what I got, I would recommend you to take a look at -logistic- and related entry in Stata 13.1 .pdf manual or scoll down Statistics from Stata menu, stop at -Survival analysis- and take a comprehensive tour in its options and their entries in Stata 13.1 .pdf manual.

[Clyde Schechter]

I think what Alex wants is:

display binomial(100, 20, 0.4)  // PROBABILITY OF 20 OR FEWER

// OR

display binomial(100, 20, 0.4) - binomial(100, 19, 0.4) // PROBABILITY OF EXACTLY 20

// OR

display 1-binomial(100, 19, 0.4) // PROBABILITY OF 20 OR MORE

[Alex Field]

Dear Carlos and Clyde. Thank you so very much for your assistance answering this question. It has really helped. Alex

[Carlo Lazzaro]

Alex:
just a belated small contribution following Clyde's methodological stream:

display 1-binomial(100, 0, 0.4)// probability of at least 1