Associate Safety Professional Practice Exam

In what scenario is Poisson distribution applicable?

1. Occurrences of an event are large

2. Occurrences of an event are small with large number of cases

3. When the total events are predictable

4. For continuous data sets

The correct answer is: Occurrences of an event are small with large number of cases

The Poisson distribution is particularly applicable when considering the number of events that occur in a fixed interval of time or space, especially when these events are rare. In scenarios where the occurrences of an event are small relative to a large number of opportunities for those events to occur, the Poisson distribution effectively models the probability of a given number of events happening. This means that in a context where events are infrequent but there is a vast pool or potential agent (like customers arriving at a store or defects in a manufacturing batch), the use of the Poisson distribution can provide valuable insights. It assumes that events occur independently and at a constant average rate, which aligns with scenarios of infrequent events happening within a large population. By contrast, other options do not align as well with the assumptions of Poisson distribution. For instance, a situation with large occurrences or predictable total events does not reflect the core characteristics of a Poisson process, which emphasizes rarity rather than abundance. Additionally, while continuous data sets are suitable for other types of distributions, the Poisson distribution is specifically discrete, dealing only with countable occurrences.