Estimating the detection limit using a probit fit

Fit 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.