A geometric distribution counts failures before the first success in independent trials.
Geometric Distribution Calculator
Form
Results
Geometric probability
0
Expectation (mean)
0
Variance
0
Standard deviation
0
Table of Contents
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What is Geometric Distribution?
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How to Use This Calculator
- Enter or select Number of failures, Probability of success.
- 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(X=k)=(1−p)ᵏp
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Variables Explained
| Input | What it means |
|---|---|
| Number of failures | The number to test or transform; use the integer or real-number domain stated in the formula. |
| Probability of success | Use the measured or stated value for this item, with the unit or category shown beside the field. |
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Worked Example
With p=0.25, exactly two failures before success has probability 0.75² × 0.25 = 0.140625.
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Why Use This Calculator?
Model the wait until a first success in repeated independent attempts.
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Common Mistakes
- Some definitions count trials rather than failures; those versions shift the index by one.
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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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