The classification scheme used here is possibly the clearest one I’ve had the chance to see, one I wish I had seen in use at every place I worked at. Here are the broad categories:
- Surrogate variable that is measured: the thing we measure because it is measurable
- Variable of true or greater interest: the thing we actually want to know about
- Measurement technique of surrogate variable: whether we have the ability to get the actual direct value, or whether it is rather inferred from other observations
- Atrefactual influences: what are the things that can mess up the data in measuring it
- Certainty of “Normal Range”: how sure are we that the value we read is representative of what we care about?
