AVG MDX Function

I have been trying to solve a calculated measure using both the sum/count methods and the avg function, but neither is working for the result that I want. We are trying to come up with an average course score based on an average test score. Example: user takes two tests (test1 twice for 50% and 100% - avg = 75% test2 once for 100%) and the course average would be (75+100)/2 = 87.5%. In our MDX we are getting (50+100+100)/3 = 83.33% instead.

We do have a hierarchy set based on course-->test-->test iteration where test iteration is each individual score. The overall average works the way you would typically thing with the sum/count method, but not based on how we want it to calculate AVG(AVG(test1 scores) + AVG(Test2 scorces)). I tried to use the AVG function, but this only works at the lowest level in the hierarchy and then appears to SUM up the results as you go up into the hierarchy (avg test1 75% test 2 100% course 175% -- not sure why the AVG works that way).

Can anyone tell me if this is even possible to get the average the way I am proposing or do I need to create some type of an aggregated take will calculations in the data warehouse to reference.

Thanks.

Seems like what you need to do is to define formula at the Test level to be Avg(Test.Children, Measures.CurrentMember), where at TestIteration level it will be Sum/Count formula. This will give you the results you are looking for.|||

I really appreciate your response and it is an honor to have you reply to this thread. I am sorry to sound stupid, but how do I define the calculations at the different levels and I am a bit confused with the Measures.CurrentMember. I guess I don't see how the testiteration level formula in the hierarchy gets passed to the other formula.

Thanks in advance.

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Here is a piece of MDX script which should do it:

CREATE AvgGrade = Measures.SumGrade / Measures.CountGrade;

(Test.Test.Test.MEMBERS, AvgGrade) = AVG(EXISTING Test.TestIteration.TestIteration.MEMBERS, AvgGrade);

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Thanks again for the quick response and I really appreciate you taking the time to assist me with this calculation. I just want to make sure I am doing this correctly. Here is what I put in the script editor:

CREATE AvgScore = Measures.[Test Scores] / Measures.[Completed Test Count];

([Fact Test Instance].[Hierarchy].[Course].[Test].Members, AvgScore) =

AVG(EXISTING [Fact Test Instance].[Hierarchy].[Course].[Test].[Iteration].Members, AvgScore)

We are currently using a hierarchy called [Hierarchy] (made up of Course-->Test-->Iteration) created off of a fact called [Fact Test Instance]. When I deploy this and drilldown to the test level I get a #VALUE!, so I am assuming I am doing something incorrectly. The other levels show the AvgScore result. Is there something wrong with my expression or does it have something to do with the solve order?

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The [Fact Test Instance].[Hierarchy].[Course].[Test] piece looks too long - there should be 3 parts - dimension, hierarchy, level and you have four parts. Is [Fact Test Instance] name of the dimension ? Then it should be

([Fact Test Instance].[Test].[Test].Members, AvgScore) = AVG(EXISTING [Fact Test Instance].[Iteration].[Iteration].Members, AvgScore);

Or another way to write it is

([Fact Test Instance].[Hierarchy].[Test].Members, AvgScore) = AVG([Fact Test Instance].[Hierarchy].CurrentMember.Children, AvgScore);

You will also need to do something similar about Course level too.

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Thanks again for your response and assistance. I modified the script to be the same as your second option and I am still getting the overall average at the test level when I browse the data within the BIDS browser using the AvgScore measure and the hierarchy called [Hierarchy] within the [Fact Test Instance] dimension. I have a student that has taken two different tests. Test1 taken twice - 33.33% and 100% for AVG 66.67% ; Test2 taken once - 90% for AVG 90% and the overall average would be (33.33+100+90)/3 = 74.44% and we would still like to get (66.67+90)/2 = 78.33%.

This definitely sounds like it should work, so is there something that I am missing or how can I validate that it is actually using this calculation at this specified level?

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From your description it sounds like you are looking above Test level, i.e. at Course level, since you want to see aggregate of two different tests. So you will also need

(AvgScore, [Fact Test Instance].[Hierarchy].Course.MEMBERS) = AVG([Fact Test Instance].[Hierarchy].Children, AvgScore);

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Once again I want to thank you so much for your assistance and you are absolutely right. I put in the additional script:

([Fact Test Instance].[Hierarchy].Course.MEMBERS, AvgScore) = AVG([Fact Test Instance].[Hierarchy].Children, AvgScore);

and I am now seeing the result that we are looking for. I am assuming that I simply have to repeat this up the hierarchy to keep this working this way. I really appreciate you taking the time to help me out with this issue.