Examples
Examples
Try the starting example
- Marked and released in first sample
- 50
- Caught in second sample
- 40
- Marked recaptures in second sample
- 10
- Chapman population estimate
- 189.090909
- Chapman variance estimate
- 1,728.099174
Try another scenario
- Marked and released in first sample
- 51
- Caught in second sample
- 40
- Marked recaptures in second sample
- 10
- Chapman population estimate
- 192.818182
- Chapman variance estimate
- 1,806.033058
Calculation method
Calculation method
Chapman population estimate
((marked+1)(caught+1)/(recaptured+1))−1, closed-population equal-catchability assumptions.
Chapman variance estimate
(M+1)(C+1)(M−R)(C−R)/((R+1)²(R+2)).
Symbols and units
- a
- Marked and released in first sample
- b
- Caught in second sample
- c
- Marked recaptures in second sample
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions & limits
Assumptions & limits
- Marked-release-recapture counts, selected model. Returns Population estimate with assumptions. All coefficients and observations are user supplied; results describe only the stated mathematical model. Quantities are deterministic calculations from supplied observations and assumptions; no external data is fetched. Supported limits: Finite inputs only; numeric fields bounded as labelled. Lists and JSON records are limited to 256 entries unless a stricter tool bound is stated. No automatic design approval, legal conclusion, treatment recommendation or safety certification. Marked and released in first sample: minimum 1, maximum 1000000. Caught in second sample: minimum 1, maximum 1000000. Marked recaptures in second sample: minimum 1, maximum 1000000.
Are these inputs private?
These calculations run in your browser. A shared link contains the values you choose to share. Only questions submitted to the separate AI finder are sent to OpenAI.