If somebody has a 25% chance of a heart attack within the next 10 years, what are the chances of their having such an attack in any given year ? Am I right that the answer = 25/10 = 2.5 ? Or have I made a statistical gaffe ?
Would the probability change as the 10 years progressed ? If someone with a 25% chance in 10 years hasn't had an attack by the 9th year, would they be more at risk in the final year ? I'm inclined to say 'no' but might a different probability apply to a random year from a final year when nothing had happened so far ? Excuse me, please, if the question is statistically ignorant.
Btw : the person isn't me.
2007-11-06 01:08:12 · 1 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
serf_tide : many thanks. It seems I'm right that the final year could carry a different probability but I can see it's not calculable from the data here. Great answer : prompt, accurate and clear.
2007-11-06 01:24:33 · update #1
Since the % is given to you over a time period, the probability of a shorter time period would be 0.25/10 = 0.025 or 2.5%. We know that time has an effect on people, but the statistics don't tell you the effect, so you have to assume that the last year is the same risk as the first, i.e. 2.5%.
2007-11-06 01:14:18 · answer #1 · answered by serf_tide 4 · 4⤊ 0⤋