EVERYDAY CLARITY
Poisson Zero Events Probability Calculator
Calculate the chance of zero events in a Poisson model from the expected event count.
Your result
Probability of zero events
Probability of one or more events
Result for the values shown.
Calculations run in your browser.
What to enter
| Input | Meaning and units |
|---|---|
| Expected number of events | Enter expected number of events using the definition in the method and example. |
Understanding your result
These outputs describe the probability model and event definitions you entered. A probability is a number from 0 to 1; a probability density is not itself the probability of one exact continuous value.
Common mistakes
- Entering 25 instead of 0.25 for a probability, or assuming events are independent when the model requires that assumption.
- Confusing an exact-count probability with a cumulative probability, or replacement with sampling without replacement.
Check your calculation
- Check a zero/certain-event boundary and the stated support of the distribution against the worked example.
Calculation checks, sources and review limits
What is the probability no events occur during this period?
Calculate the chance of zero events in a Poisson model from the expected event count.
Common uses
- What is the probability no events occur during this period
How it works
zero = exp(0 - expected); atLeastOne = 1 - zero
Worked example
Enter Expected number of events: 2 . Results: Probability of zero events: 0.1353352832366127 ; Probability of one or more events: 0.8646647167633873 .