Joint probability describes the chance that both events occur.
Joint Probability Calculator
Form
Results
P(A and B)
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Table of Contents
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What is Joint Probability?
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How to Use This Calculator
- Enter or select P(A), P(B).
- Check the unit beside each measurement. For a percentage or rate, use the scale and time period stated in the form.
- Choose Calculate, then compare the output with the formula and example below. If you change a value or option, calculate again to update the result.
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Formula Used
P(A and B)=P(A)P(B), if A and B are independent.
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Variables Explained
| Input | What it means |
|---|---|
| P(A) | The chance of event A; use the form’s percentage or decimal convention. |
| P(B) | The chance of event B on the same probability scale as the other inputs. |
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Worked Example
Independent probabilities 0.4 and 0.5 give a joint probability of 0.2.
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Why Use This Calculator?
Combine two independent event chances without adding incompatible probabilities.
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Common Mistakes
- The form accepts percentages: enter 40 and 50 for 40% and 50%. The multiplication rule assumes independence; dependent events need a conditional probability.
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Frequently Asked Questions
Does a calculated statistic prove a conclusion?
A statistic describes the supplied data under stated assumptions. Sampling design, missing observations and the suitability of the model still determine what can reasonably be concluded.
Should I include every observation?
Use the observations required by your study design and state any exclusion rule. Removing values only because they change the answer can bias the analysis.
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Sources & References
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