How are Health Index Exception Points calculated?
Health Index exception points are points assigned based on a logarithmic equation. The number of exception points that eHealth assigns to an element depends on the health index that the element receives for a health index variable. For example, an element with few errors for a report period would receive a low health index for errors and few or no exception points. If that same element experienced a high percentage of errors during the day, it would most likely receive a high health index and all 66 exception points. Elements rarely experience extreme problems that would cause eHealth to assign the maximum health index for the entire report period. To ensure that it assigns the appropriate number of exception points to all error conditions, eHealth aggressively assigns exception points to lower health indexes using a logarithmic equation.
To verify the Health Index Exception Points assigned to a given element, do the following:
1. Sum the Hourly Health Index averages for the specified element for the time range of the report
2. Take that summed Health Index value and enter it into the following formula: log10(summedHealthIndex)/log10(192)
3. Multiply the result from #2 by 66 Total Possible exception points
Note: Most Health reports will use the default maxPoints value of 192. However, since maxPoints is tune-able, the value may differ from 192 depending on the technology involved or whether the report or service profile in use were customized.
EXAMPLE: The element in question was assigned 25.2 Health Index Exception Points as per the eHealth report that was sent in.
Here is how the value of 25.2 was calculated:
1) Sum the hourly health index averages for the element for the day
The element had a health index of 4 @ 1AM, 2.6637 @ 7PM and 0.797865 @ 8PM
7.461565 = 4+2.6637+.797865
This value is summedHealthIndex in the following calculation.
2) Take the value of # 1 and enter it into the following formula:
log10(summedHealthIndex)/log10(maxPoints) # maxPoints is tune-able, but set by default to 192.
0.382267 = log10(7.461565)/log10(192)
The 192 in step 2 represents a reasonable maximum number of exception points of 8 points per hour.
3) Multiply the value of step 2 by 66, the maximum number of health index exception points.
25.2296 = 0.382267 * 66
For more information regarding which element types have configurable Availability and Unavailability ranges, see solution TEC515606