Minimum

What would happen?

First, the two examiners may start quarreling. That's the least of our interest.

More importantly, the two would end up setting the minimal standard as measuring the blood pressure - the only common factor agreed by the two.

What's wrong with this minimal standard? None, as long as you know how to use it.

Most examiners (who are, unfortunately, not properly trained) would take it as the criteria of passing a student. In other words, any candidate who does measure blood pressure in this station passes.

But, that's wrong. In the jargon of logic, the minimal standard should be a necessary criteria, but not a sufficient one, of passing. In other words, a candidate should always fail if he does not measure the blood pressure, but he should not automatically pass if he measures - unless he also makes sure the patient does rest enough and confirms the timing of blood pressure medicine, or he measures blood pressure from both arms and look for postural drop. If the minimal standard is not used in this way, it would inevitably end up having a set of stupid criteria and a bunch of dumb graduates.

PS. The whole situation is actually a variant application of the inverse marking scheme widely used for assessing practical procedures. Interested readers may like to a previous blog of mine. (See http://ccszeto.blogspot.com/2010/10/marking.html)