Suitability tests

About suitability tests

Suitability tests support you in ensuring that your analysis produces valid and reliable results. They define criteria that the data have to meet for the calculated outcomes to be considered scientifically sound and trustworthy.

In dose-response analysis, suitability tests are essential for verifying the integrity of both the overall assay and individual samples. They help detect issues such as poor curve fitting or unexpected sample behavior before reporting results.

PLA 3.0 supports the following types of suitability tests:

Assay suitability tests: These tests are conceptually similar to system suitability tests. They assess the performance of the overall assay. You use them to ensure that the regression model fits the data and that the Standard curve lies in the verified space. If an assay suitability test fails, PLA 3.0 rejects the entire assay.
Sample suitability tests: These tests evaluate individual assay elements. You use them to qualify samples to the analytical method. If a sample suitability test fails, PLA 3.0 rejects only the respective sample only.

Note: For a detailed description of the available suitability tests, see the Test system definition topic.

Test scope

By default, PLA 3.0 applies suitability tests to all assay elements. Use the scope to configure the default behavior as you require. The following scopes are available:

Assay element type scope: Use this scope if you want to run the test for specific assay element types, that is, Standard, Test, or Control.
Assay element scope: Use this scope if you want to run the test for an individual assay element.

The following example uses an assay with four samples, that is, one Standard, two Test samples, and one Control sample. The test in question is an F-test for the lack of fit. The following figure shows the coverage of the test system depending on the test scope:

Diagram with three test scope models labeled A, B, and C. Panel A shows Standard, Test 1, Test 2, and Control elements in dark teal, indicating scope across all assay elements. Panel B shows Standard and Control in light blue with Test 1 and Test 2 in dark teal, defining scope limited to Test samples only. Panel C shows Test 1 in dark teal and Standard, Test 2, and Control in light blue, indicating scope restricted to Test 1 assay elements. — Figure 1. Sample test scope setup

Setup A uses the Assay element type scope with the All assay elements option. The test therefore applies to all samples.
Setup B uses the Assay element type scope with the Test samples only option. The test therefore applies to all Test samples, not to the Standard and Control sample.
Setup C uses the Assay element scope with the Test sample 'Test 1' as the reference. The test therefore applies to this Test sample only.

Note: Which assay elements are included in a test also depends on the test type. Some tests are only performed for particular types of assay elements. Moreover, the model determines which tests are feasible. Some test definitions may not work with your model.

Severity level

The severity level of a test describes the impact of a failed test on the overall result of the assay evaluation. Use it to control how failed tests affect the results. PLA 3.0 supports three different severity levels for tests:

Reject: If the test fails, no interpolated concentrations and additional calculation results are reported. For reporting the overall test result, the test is considered 'Rejected.'
Warning: If the test fails, interpolated concentrations and additional calculation results are reported. For reporting the overall test result, the test is considered 'Failed.'
Information: If the test fails, interpolated concentrations and additional calculation results are reported. For reporting the overall test result, the test is considered 'Passed (info available).'

PLA 3.0 determines an overall test result from the severity levels of failed tests, as indicated in the following table:


Overall test result	Failed tests of severity level 'Rejected'	Failed tests of severity level 'Warning'	Failed tests of severity level 'Information'
Passed	0	0	0
Passed (info available)	0	0	≥1
Failed	0	≥1	any number
Rejected	≥1	any number	any number

Note: If more than one test fails, the overall result is controlled by the failed test with the highest severity level.

Work with suitability tests

For details on how to create and work with suitability tests, see the Create suitability tests topic.