Probit LD50 Estimate
Calculate LD50 from a fitted probit-5 model of the form probit = intercept + slope × log10(dose). Fifty percent response is probit 5, so LD50 = 10^((5 − intercept)/slope).
Description
Calculate LD50 from a fitted probit-5 model of the form probit = intercept + slope × log10(dose). Fifty percent response is probit 5, so LD50 = 10^((5 − intercept)/slope).
Probit LD50 Estimate is a focused biology tool that calculate LD50 from a fitted probit-5 model of the form probit = intercept + slope × log10(dose). Fifty percent response is probit 5, so LD50 = 10^((5 − intercept)/slope). It calculates locally from the values you enter and exposes the result without changing the source observations.1
When to use Probit LD50 Estimate
Use Probit LD50 Estimate when you need to calculate LD50 from a fitted probit-5 model of the form probit = intercept + slope × log10(dose). Fifty percent response is probit 5, so LD50 = 10^((5 − intercept)/slope). Enter Probit intercept and Probit slope using the definitions and units below so the result can be reproduced.
- Probit intercept
- Intercept of the fitted probit-5 regression at log10(dose) zero.
- Probit slope
- Positive slope of probit response against log10(dose).
How Probit LD50 Estimate calculates the result
The published tool contract uses this rule: Calculate LD50 from a fitted probit-5 model of the form probit = intercept + slope × log10(dose). Fifty percent response is probit 5, so LD50 = 10^((5 − intercept)/slope).1
- LD50 estimate
- Estimated dose that produces a response in half the population.
Limitations of Probit LD50 Estimate
The output is an estimate tied to the stated model and coefficients; it is not a direct measurement and should retain that label when reported. It is informational and cannot diagnose a condition, select treatment, or replace professional interpretation of the original measurements.
Alternative or Complementary measurements
Retain the original Probit intercept and Probit slope values and their units alongside the result. LD50 Log-Dose Interpolation is useful when you instead need to estimate LD50 by linear interpolation of response against log10 dose between an ordered lower point at or below 50% mortality and an ordered higher point at or above 50%. This is a two-point estimate, not a fitted dose-response model. Turgor Pressure Estimate provides another view by helping you estimate turgor pressure in megapascals as the total water potential minus the osmotic potential, floored at zero when the cell is flaccid; both potentials are signed and finite.
References
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Median lethal dose — Wikipedia contributors
Similar or alternative tools
- LD50 Log-Dose Interpolation
Estimate LD50 by linear interpolation of response against log10 dose between an ordered lower point at or below 50% mortality and an ordered higher point at or above 50%. This is a two-point estimate, not a fitted dose-response model.
- Turgor Pressure Estimate
Estimate turgor pressure in megapascals as the total water potential minus the osmotic potential, floored at zero when the cell is flaccid; both potentials are signed and finite.
- Total Blood Volume Estimate
Estimate total blood volume from body weight using the documented reference value of 70 millilitres per kilogram.