rate of change

Using the functions differences between and fractional years between episodes we can build Calculated Values for the rates of change of other values. For example,
suppose that we have an attribute HDL. We need to define two Calculated Values:

DeltaHDL = differences between HDL

YearsBetweenTests = fractional years between numeric HDL episodes

Then we can build a rate of change Calculated Value in terms of these two:

RateOfChangeHDL = DeltaHDL / YearsBetweenTests

These calculated values would then appear in the case as follows:

We could also define a cumulative rate of change function using differences from first and fractional years between first and subsequent episodes functions:

NettRateOfChange = (differences from first HDL) / (fractional years between first and subsequent numeric
HDL episodes)

In this example we have defined the rate of change Calculated Value without defining intermediate Calculated Values for the numerator (differences) and denominator (time). We could have adopted this approach in our RateOfChange Calculated Value:

RateOfChangeHDL = differences between HDL / fractional years between numeric HDL episodes