Hi Emma,

If all you want is for the calculation to be one calculation versus three, then use the following:

((Avg([Satisfaction Score]))-(window_sum([Team Mean Score])/total(countd([Team])))) /

SQRT(window_sum(square([Team Mean Score]-[Mean of Population])) /

total(countd([Team])))

Hope this helps!

-Tracy

Here is a simplification of your Z Score formula:

(

AVG([Satisfaction Score])

-

WINDOW_AVG(AVG([Satisfaction Score]))

)

/

WINDOW_STDEVP(AVG([Satisfaction Score]))

The difference from average divided by the standard deviation of the population.

As for the difference between stdev and stdevp, a quick Google search turned up:

Quote:

• STDEV is used when the group of numbers being evaluated are only a partial sampling of the whole population. The denominator for dividing the sum of squared deviations is N-1, where N is the number of observations ( a count of items in the data set ). Technically, subtracting the 1 is referred to as "non-biased."
  
  
• STDEVP is used when the group of numbers being evaluated is complete - it's the entire population of values. In this case, the 1 is NOT subtracted and the denominator for dividing the sum of squared deviations is simply N itself, the number of observations ( a count of items in the data set ). Technically, this is referred to as "biased." Remembering that the P in STDEVP stands for "population" may be helpful. Since the data set is not a mere sample, but constituted of ALL the actual values, this standard deviation function can return a more precise result.

It would be best if you could supply a sample packaged workbook, that represents your situation, and the numbers you expect as a final result from the sample data provided. Thank you.