1. Statistical Reference Guide
  2. Measurement systems analysis (MSA)
  3. Detection capability

Estimating the detection limit using a probit fitFit a probit regression model to estimate the limit of detection.

  1. Select a cell in the dataset.
  2. On the Analyse-it ribbon tab, in the Statistical Analyses group, click Fit Model, and then click Probit.
    The analysis task pane opens.
  3. In the Y drop-down list, select the binary response variable.
  4. In the Event drop-down list, select the positive outcome.
  5. In the X drop-down list, select the level variable.
  6. Next to the X drop-down list, click the drop-down menu, and then in the Transform drop-down list, select Log 10
  7. In the Plot drop-down list, select Scaled - X against Y.
  8. Clear the Individual check box, and select the Aggregate check box.
  9. On the Analyse-it ribbon tab, in the Fit Model group, click Predict, and then click X given Probability.
  10. On the analysis task pane, in the Fit panel, in the Predict X given Probability edit box, type 0.95
  11. Click Calculate.
On the analysis report, in the Predict X for Given Probability section, the predicted level at 0.95 probability is the limit of detection.
Available in
Method Validation Edition Ultimate Edition

From the Statistical Reference Guide for Analyse-it 6.24.0: https://analyse-it.com/docs/user-guide/measurement-systems-analysis/detection-capability/fitting-detection-limitprobit-regression

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