DNA Random Match Probability Calculator
Toy independent-locus Hardy-Weinberg random-match product p²/2pq with externally validated population frequencies; excludes theta, mixtures, relatives, dropout/errors and likelihood ratios; never identity or guilt determination.
Description
DNA Random Match Probability Calculator: return locus genotype probabilities, log10 random match probability, random match probability, identity determined.
A random-match probability concerns how often a genotype might occur under a population model. It is not a probability that a particular person is innocent or guilty.1
This tool returns locus genotype probabilities, log10 random match probability, random match probability, identity determined. Use the stated units and model convention when interpreting these fields.
When to use this tool
Use this tool when the supplied inputs match the specific operation described above and you need a repeatable result under its stated convention.
- Check the supported input and output contract against an existing calculation or observation.
- Use the complete example to confirm units, selector spelling and result interpretation.
How to use the tool and how it works
- Enter every field in the input table using the stated units and the exact supported selector spelling where applicable.
- Run the tool. Correct input errors before interpreting an output.
- Read the result fields below; use accompanying flags and the stated sign, boundary or model convention when interpreting a number.
Use p squared for a homozygous locus and 2pq for a heterozygous locus, then add base-10 logarithms across loci. Report individual locus probabilities, the logarithm and its exponentiated product.2
| Input field | Meaning and units | Accepted input |
|---|---|---|
| genotypeKinds | Genotype kinds. | List of text values |
| alleleAFrequencies | Allele a frequencies. | List of finite numbers |
| alleleBFrequencies | Allele b frequencies. | List of finite numbers |
| Output field | Interpretation |
|---|---|
| result | Object containing the following named result fields. |
| result.locusGenotypeProbabilities | Locus genotype probabilities list, in the ordering described in the calculation. |
| result.log10RandomMatchProbability | Log10 random match probability; use the stated units and sign convention. |
| result.randomMatchProbability | Random match probability; use the stated units and sign convention. |
| result.identityDetermined | Always false; a random-match model does not establish personal identity. |
{
"input": {
"genotypeKinds": [
"homozygous",
"heterozygous"
],
"alleleAFrequencies": [
0.1,
0.2
],
"alleleBFrequencies": [
0.1,
0.3
]
},
"output": {
"result": {
"locusGenotypeProbabilities": [
0.01,
0.12
],
"log10RandomMatchProbability": -2.9208187539523753,
"randomMatchProbability": 0.0012,
"identityDetermined": false
}
}
}Limitations and assumptions
- The calculation assumes Hardy-Weinberg proportions and independent loci, without population-structure or relatedness corrections. Very small ordinary probabilities can underflow; identityDetermined remains false.
- Every declared field is required and unexpected fields are rejected. Numeric inputs must be finite; input errors are distinct from a valid false result or an explicitly qualified output.
- Extremely large inputs and nonfinite or excessively large outputs are rejected. List positions reported by the tool use zero-based indices unless stated otherwise.
Alternative or Complementary methods
Check the underlying observations, units and conventions independently before using the result in a larger workflow. The tools listed below address nearby tasks; compare their inputs and scope before substituting one for this operation.
References
-
DNA Mixture Interpretation: A NIST Scientific Foundation Review — population models and random-match probability — National Institute of Standards and Technology
-
Tool behavior and example: DNA Random Match Probability Calculator — tool.io
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