# Probability of an Event...in a certain Time!

#### SMITH1988CJ

##### New Member
Hi Guys,

This is probably a basic question for you lot...but let's say I had calculated the chance of an event happening (in this case lets say a goal for a specific team in a football match...) as being 40% at any point in that game. Then I have also worked out that based on all the goals they score, they score 35% of all of them in the first half of their games...

How do I calculate the percentage chance of them scoring in the first half of the next game? Is it simply .4 multiplied by .35 then multiplied by 100?

My follow on question would then be...that works out as 14%...the second half would then be .4 multiplied by .65 yes? Resulting in 26%?

Any help much appreciated!

Chris

#### Masteras

##### TS Contributor
P(goal scored)=0.4 P(goal in the 1st half) = 0.35
P(goal in the 1st half | goal is scored) = P(goal in the first half, goal is scored)/P(goal is scored) =(0.4*0.35)/0.4

#### Miner

##### TS Contributor
If you have data that records the time to each event, I would use reliability statistics to answer that question. Reliability analysis is all about the time to an event with associated probabilities.

#### Masteras

##### TS Contributor
I think he does not know what is reliability analysis. It looks to me as a simple question.

#### rogojel

##### TS Contributor
hi,
if you take A to be scoring in the first half and B scoring a goal then you are interested in P(A).
This would be P(A)=P(A|B)*P(B)+P(A|notB)*P(notB)

P(A|notB) is obviously zero so you would be left with the first term which would be 0.35*0.4=0.14