Hilmar Buchta

SQL Server 2008

Although the way of defining the KPI status and trend is very flexible it is also somehow circumstantial if you simply want to rate a KPI by its target value. In this case you would have to calculate the status of the KPI as being between –1 (worse) and +1 (best).

In many cases we find simple case statements here:

case
when KPIVALUE("TestKPI") >= 0.95 * KPIGOAL("TestKPI") then 1
when KPIVALUE("TestKPI") < 0.7 * KPIGOAL("TestKPI") then -1
else 0
end

This results in the KPI status being –1, 0 or +1. But if you want to blend smoothly between these values you have to use a formula that is a little bit more complex. Especially  if you need to this computation for many KPIs it’s not really nice.

I had some examples for AS stored procedures (sprocs) in this blog before. So here is a very simple one to calculate a linear approximation between the boundaries:

public static double KPIStatusBanding(double bound1, double bound2, double actual)
{
    double factor=0;

    if (bound1 < bound2) factor = 1;
    else if (bound1 > bound2) factor = -1;
    else return 0;

    if (actual < bound1) return -factor;
    else if (actual > bound2) return factor;
    else return factor*2 * (actual – bound1) / (bound2 – bound1) – 1;
}

The parameters are as follows:

bound1 worst value
bound2 best value
actual actual value

 

image

If bound1 < bound2 bigger values are better, if bound1 > bound2, lower values are better. With this function the calculation is quite easy. First let’s test the function itself with simple MDX queries:

with
member test as ASStatistics!KPIStatusBanding(100,200,175)
select test on 0
from [Adventure Works]

This results in a status value of 0.5.

In order to use the same boundaries as in my first example, I would use this KPI status expression:

ASStatistics!KPIStatusBanding(
0.7 * KPIGOAL("TestKPI"),
0.95 * KPIGOAL("TestKPI"),
KPIVALUE("TestKPI"))

image

As we can see from the KPI browser the values now gets approximated smoothly:

image