Finally, suppose that at some point the Doctor undergoes the ogt-test herself,
and takes actual measurements 
and 
, representing her
fasting blood-glucose level and two-hour blood-glucose level. We write
these measurements as a vector 
, where
Notice immediately that the Doctor is classified as having impaired glucose tolerance because of her reading of 9.8. Indeed, she is very close to being classified as diabetic. Let us reiterate that whilst this example is purely illustrative, it is genuine: these are real observations for a ``randomly chosen'' elderly person with no history or indication of diabetes.