Scientific methods
Probit Analysis
Dose/concentration-response analysis for bioassays run at several concentrations or doses. Independently validated and released for research use.
Released for research use
Illustrative laboratory image. It shows no experimental data.
About the method
VectorBio fits a grouped-binomial probit model on log10 exposure, with a fixed background mortality, and estimates the endpoints you request together with 95% Fieller confidence limits.
The method follows the classical probit approach described by Finney. It is a statistical analysis method; it is not a WHO-defined procedure.
How it works in VectorBio
Set the context
Choose a concentration (LC) or dose (LD) profile and enter the taxon, active ingredient and exposure unit. Laboratory records can be linked when you save.
Enter the series
Record the number exposed and the number dead at each concentration or dose.
Choose endpoints
Request endpoints such as the 50%, 90%, 95% or 99% response levels.
Analyze and review
Review the fit, endpoint estimates, warnings and the dose-response chart.
Save
Save stores an immutable record that you can reopen and export.
What the result shows
- Fitted intercept and slope
- Requested endpoint estimates with 95% Fieller confidence limits
- Heterogeneity check, with variance adjustment only when you enable it
- Warnings when an endpoint lies outside the tested exposure range or has weak response support
- A two-dimensional dose-response chart of the observed data and fitted curve
Scope
- When the data cannot support a reportable estimate, for example a non-positive slope, separation or an unbounded confidence interval, VectorBio says so instead of reporting endpoints.
- Probit results are research outputs. VectorBio does not assign resistance categories from them and does not present them as regulatory determinations.
What a saved result looks like
The structure of a saved result in the VectorBio application. Field names are taken from the released interface; values appear only in your own Workspace.
Result
LC/LD analysis
Possible values
- Reportable
- Reportable with warnings
- Not reportable
- Species / taxon
- Value recorded in the saved analysis
- Active ingredient
- Value recorded in the saved analysis
- Unit
- Value recorded in the saved analysis
Response profile
Profiles
- Concentration / LC
- Dose / LD
Endpoint estimates · LC/LD50
- Estimate
- Value recorded in the saved analysis
- 95% confidence interval
- Value recorded in the saved analysis
Model summary
- Slope (β)
- Value recorded in the saved analysis
- Intercept (α)
- Value recorded in the saved analysis
- Dispersion (φ)
- Value recorded in the saved analysis
- Heterogeneity
- Value recorded in the saved analysis
Analysis warnings
Possible values
- An endpoint lies outside the tested exposure range
- Weak response support for an endpoint
- Heterogeneity detected
Dose-response
Response (%)
Exposure (unit) · log scale
Observed data and the fitted curve are drawn from your own analysis.
Evaluate VectorBio with your own workflow
Request a trial and ZIDRA will prepare a dedicated Workspace for your organisation, or ask for a quotation for organisational access.