Mean Probability Calculator

Measure expected outcomes from discrete probability models quickly. See spread, thresholds, and weighted behavior instantly. Make sharper forecasts with clear distribution evidence every time.

Distribution Inputs

Use discrete values and their probabilities to estimate the expected mean and related statistics.

Responsive 3 / 2 / 1 column calculator

Outcome Row 1

Outcome Row 2

Outcome Row 3

Outcome Row 4

Outcome Row 5

Example Data Table

This sample shows a valid discrete probability distribution for expected-value analysis.

Value (x) Probability P(x) x × P(x)
0 0.1 0
1 0.2 0.2
2 0.35 0.7
3 0.2 0.6
4 0.15 0.6

Formula Used

Mean or expected value: μ = Σ[x × P(x)]

Second moment: E[X²] = Σ[x² × P(x)]

Variance: σ² = E[X²] - μ²

Standard deviation: σ = √(σ²)

Cumulative probability: Sum the probabilities of all qualifying outcomes for your threshold rule.

How to Use This Calculator

  1. Enter each discrete outcome in the value fields.
  2. Enter the matching probability for every outcome row.
  3. Use normalization if your probabilities do not total exactly 1.
  4. Set low and high thresholds for extra cumulative probability checks.
  5. Press the calculate button to display results above the form.
  6. Download the result table as CSV or save a PDF report.

Frequently Asked Questions

1. What does the mean probability result represent?

It represents the expected value of a discrete random variable. The calculator multiplies each outcome by its probability, then adds those weighted contributions.

2. Do the probabilities need to add up to 1?

Yes, a valid probability distribution totals 1. You can also enable normalization, and the calculator will rescale the entered probabilities proportionally.

3. Can I use negative outcome values?

Yes. Outcomes may be positive, negative, or zero. The calculator still computes the expected mean, variance, and threshold probabilities correctly.

4. What is the difference between mean and variance?

The mean measures the weighted center of outcomes. Variance measures how widely the outcomes spread around that center after accounting for their probabilities.

5. Why are threshold probabilities useful?

They help evaluate risk ranges and decision boundaries. You can estimate the chance of staying below, above, or within limits using your distribution.

6. Is this calculator suitable for discrete data only?

Yes. It is designed for discrete outcomes with listed probabilities. Continuous distributions usually require density functions and integration instead.

7. What happens if the mean is zero?

The coefficient of variation becomes undefined because it divides the standard deviation by the mean magnitude. Other statistics still remain available.

8. Can I export my results for reporting?

Yes. Use the CSV button to save the result table data and the PDF button to print or save a formatted report for sharing.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.