Exercise: Find the average ratio between square metre area and units

This exercise is provided to allow potential course delegates to choose the correct Wise Owl Microsoft training course, and may not be reproduced in whole or in part in any format without the prior written consent of Wise Owl.

The answer to the exercise will be included and explained if you attend the Wise Owl course listed below!

Category ==> Power BI - Excel 2013  (25 exercises)
Topic ==> The CALCULATE function  (4 exercises)
Level ==> Harder than average
Course ==> PowerPivot / Excel Power BI
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If you haven't already done so, run the SQL script in the above folder (copying and commercial use prohibited) to generate a database called MAM.

Create a new workbook, and in this create the following PowerPivot data model:

Centres and centre types

Import two tables: centres and centre types.

Create a pivot table showing the average square metre area for centre types, and also the average number of units:

Average area and units

The figures by type of centre.

No need to create any calculated fields for this: you can just include the relevant fields in the VALUES section of the pivot table and change the Value Field Settings so that Excel averages, not sums, the data.

Now create a calculated field called FalseAverage which divides one of these implicit measures by the other:

Creating false average

The implicit measures will appear in autocompletion.

 

This gives you the average ratio of floor area to number of units, but it's wrong:

False average in pivot table

The true average for any cell should be the average of the total square metres for that cell's query context divided by the total number of units for that cell's query context.

Create a calculated field called TrueAverage which uses the AVERAGEX function to calculate the average of the metres-to-units ratio:

True average

The figures are different.

The shopping centre figures are returning an error because one of the centres (Market Quay, as it happens) has 0 units in the database.  To get round this, amend your true average so that it omits any figures where the number of units is 0.

You can do this by wrapping your AVERAGEX function in a CALCULATE one.

The final figures should look like this:

Final averages

The figures are the same for the 3 centre types which didn't have an error - as indeed they should be, as nothing has changed for these.

Save this workbook as Very average, then close it down. 

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