Title: probit
Long Title: IUPAC Gold Book - probit
DOI: 10.1351/goldbook.14953
Status: current

Definition
Probability unit obtained by adding 5 to the normal deviates of a standardized normal distribution of results from a dose-response study.

Notes
1) Addition of 5 removes the complication of handling negative values.
2) A plot of probit against the logarithm of dose or concentration gives a linear plot if the response follows a logarithmic normal distribution. Estimates of the \(\pu{LD_{50}}\) and \(\pu{ED_{50}}\)) (or \(\pu{LC_{50}}\) and \(\pu{EC_{50}}\)) can be obtained from this plot.

Related Term
- probit (log) transform: https://goldbook.iupac.org//terms/view/14954

Source
- PAC, 2009, 81, 829. 'Glossary of terms used in ecotoxicology (IUPAC Recommendations 2009)' on page 932 (https://doi.org/10.1351/PAC-REC-08-07-09)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/14953/html
- json: https://goldbook.iupac.org/terms/view/14953/json
- xml: https://goldbook.iupac.org/terms/view/14953/xml

Citation: Citation: 'probit' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.14953
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Accessed: 2026-04-18T19:22:51+00:00