Measurements in chartevents where error = 1

[tompollard]

Our understanding is that a value of 1 in the error column of chartevents indicates an erroneous measurement. There are several scripts in the code repo that don't exclude these measurements, but which probably should.

[tompollard]

The following clause is not good, because it excludes rows where the error field is NULL.

FROM chartevents
WHERE error != 1

Instead we can do:

FROM chartevents
WHERE error IS DISTINCT FROM 1