PODLOD-interlab by Wilrich & Wilrich

POD function and LOD of a binary microbiological measurement method from an interlaboratory experiment

according to B. Jarvis, C. Wilrich and P.-Th. Wilrich, in: Journal of AOAC International 102(5), 1617‑1623 (2019).

General information on the experiment
Name of experiment:
Date of experiment:
Microorganism:
Unit of microorganism count: ¹
Matrix:
Sample size A₀ ² in g:
Unit of the sample size: ¹
No. of laboratories:
No. of inoculation levels:
Input of inoculation levels: ³
¹ The units are set to 'CFU' and 'g' but can be changed.
² The sample size A₀ is also called test portion size.
³ Select from the drop-down list: The inoculation level may be entered either per sample size or per unit of the sample size, please see step 4 in 'How to use this calculator'.

How to use this calculator

For reliable results, at least 3 informative inoculation levels should be used. A blank and a positive control might be used in addition. For information on the design and evaluation of the experiment, see PODLOD-interlab Info.
Enter information and data on the experiment into the yellow cells of the general input table.
- Informative: Name, date, microorganism and matrix; they will be automatically included in the results.
- Required: No. of laboratories and inoculation levels, sample size and input of inoculation levels, see step 4.
Click the 'Generate' button ➤ Tables for the input of your test results are generated.
Enter your data into the yellow cells of the input tables generated according to step 3.
- The inoculation level d may be entered either per sample size in CFU/A₀, or per unit of the sample size in CFU/g ➤ The other value for d will be included in the respective other column of the input tables upon calculation.
- 'Copy' button: Input data of that table is copied to the next table (to facilitate your input).
Click the 'Calculate' button ➤ A table with the mean calculation results, a graph of the mean POD curve and its confidence and expectation bands and a table with the results for the individual laboratories are generated.
You can change data in the yellow tables at any time.
- 'Generate' button: The no. and size of the input tables are up-dated while previous input data is preserved. The 'Copy' buttons and the notes (that are removed upon calculation) are shown again.
- 'Calculate' button: A new calculation is performed with the (changed) input data.
- 'Clear' button: All previous input data are cleared.
Click the 'Save' button ➤ The tables and the graph are saved into a pdf-file upon selecting "Save as pdf' in the print menu.

'Example' buttons (see top right): Data from the reference and the alternative method as given in the publication: B. Jarvis, C. Wilrich & P.-Th. Wilrich, Journal of AOAC International, 2019, 102(5), 1617-1623 are displayed. This overwrites input data but the back button of your browser (possibly twice) will bring you back to your data.

If you have suggestions for PODLOD-interlab or found a bug, please e-mail to news@statistics-wilrich.info.

For further information and the equations used see PODLOD-interlab Info in the bottom menu.

These PODLOD-interlab results are based on the input data shown in the following / on the following page:

Statistical programs by Wilrich & Wilrich

POD function and LOD of a binary microbiological measurement method from an interlaboratory experiment

How to use this calculator