Testing the Test

 

Testing Features. We are constantly taking tests, giving them, or reading about them.  Let’s get the outcomes straight. That is, let’s learn the testing buzzwords.  In this way, you’ll know what to look for when somebody proposes a test for something, or gives you some test results.  For example, COVID-19 testing is replete with hidden meanings and outcomes.

·        Sensitivity: Ability to test correctly for the disease (or whatever).

·        Specificity: Ability to test correctly for no disease (or whatever).

From these we have

·        True positive: the test is positive for disease and disease is present.

·        True negative: the test is positive for no disease and no disease is present.

·        False-positive: the test is positive but no disease is present.

·        False-negative: the test is negative but the disease is present.

 

·        Validity: test measures what it is supposed to test. There are at least five types of validity:

o   Face validity refers not to what the test measures, but what the test ‘appears to measure’

o   Content validity tests concordant and consistent with the curriculum

o   Concurrent: test agrees with other test performance

o   Factorial validity: the extent of correlation of the different factors with the whole test.

·        Predictability: test predicts certain future outcomes, another type of validity.

Thus, some tests can valid but not predictive. For example, a test too difficult for all so that all fail.