DAX - compare selected group averages with category averages - excel

Question

I have data on objects which belong to different categories. I want to be able to compare the average across a selection of objects to averages across the categories where selected objects belong. I have written out measures, but they do not produce the expected results,
My data looks like this. I am using Power Pivot to set up the data model for MS Excel pivot charts.
Table 1 has unique stores (Store names are guaranteed to be unique)
Store
Branch
Region
Store A
North 1
Plain
Store B
North 1
Plain
Store K
West 3
Plain
Store F
West 3
Plain
Store T
East 1
Coast
Store P
East 1
Coast
Table 2
Store
Area, sq ft
Store A
3000
Store B
4000
Store K
2000
Store F
5000
Store T
5000
Store P
4000
Table 3
Store
Year
Month
Expenses
Store A
2022
September
10000
Store A
2022
October
15000
Store B
2022
September
20000
Store B
2022
October
22000
There is more than one year included in the dataset.
Table 2 and 3 are connected to table 1.
First, I write measures that I expect to compute costs per sq ft for selected objects.
Costs:=sum('Table 3'[Expenses)
Area:= sum('Table 2'[Area, sq ft])
Costs_per_sq_ft:= [Costs] / [Area]
Then, I write identical measures for averages:
Costs_avg:=average('Table 3'[Expenses)
Area_avg:= average('Table 2'[Area, sq ft])
Costs_per_sq_ft_avg:= [Costs_avg] / [Area_avg]
Finally, I write define measures to average across a selected group (assuming all selected elements belong to the same category):
Costs_avg_branch:=var StoreBranch = max('Table 1'[Branch] = StoreBranch) return calculate([Costs_avg], filter(all('Table 1');'Table 1'[Branch] = StoreBranch))
Area_avg_branch:=var StoreBranch = max('Table 1'[Branch] = StoreBranch) return calculate([Area_avg], filter(all('Table 1');'Table 1'[Branch] = StoreBranch))
Costs_per_sq_ft_avg_branch:=var StoreBranch = max('Table 1'[Branch] = StoreBranch) return calculate([Costs_per_sq_ft_avg], filter(all('Table 1');'Table 1'[Branch] = StoreBranch))
and identical measures for Region as variable,
On selection of Store A and September 2022, I expected to have
Costs_avg
Costs_avg_branch
Store A
3.33
4.28
i.e. the average for the selected store and the average for the branch where it belongs.
On selection of Store A and September-October I expected to have:
Costs_avg
Costs_avg_branch
Store A
4.17
4.78
( average over chosen period for a selected store and the same average for the branch).
On selection of the entire branch I intended the average across selection to match that of the category. E.g., for stores A, B in September-October 2022:
Costs_avg
Costs_avg_branch
North 1
4.78
4.78
Unfortunately, the averages for individual selected objects seem to be consistently near zero. When I select entire branches, the object average and the branch average do not match.
Is there any way to obtain the correct averages? Is it possible to get the desired behavior when objects from different categories are selected, as I originally wanted?