The rate of occurrence for a condition can be expressed as the odds or the percentage of a population involved.
total population =
= (number affected) + (number unaffected)
odds denominator =
= (total population) / (number affected) =
= 1 + ((number unaffected) / (number affected))
odds =
= 1 in (odds denominator)
= (number affected) to (number unaffected)
percent affected =
= (number affected) / (total population) * 100% =
= 1 / (odds denominator)
where:
• Odds = probability that an event will occur divided by the probability that the event will not occur (1 - probability).
• The probability for an event is the fraction of the event seen in many trials.
