Set Analysis/Filtering Issue

[#1]

Please see attached. I'm having an issue whereby my set analysis on a column value in a straight table is causing my filter to work in an undesirable manner. I've distilled the issue into the attached example and application.

I have a straght table with item and period (year/month) as dimensions. I have a stock value and, for each period, the number of months since the last sale. My two table expressions are:
1. =only(months_since_last_sale)
2. =avg({<period=,months_since_last_sale=>} stock_value)

But because of months_since_last_sale= in the set analysis on the second expression, all items remain when a months_since_last_sale value is selected. Ideally, the other items should disappear when a value is selected.

Here is my data:

item, period, stock_value, months_since_last_sale
Shoes, 201510, 10, 0
Shoes, 201511, 10, 0
Shoes, 201512, 20, 1
Socks, 201510, 5, 1
Socks, 201511, 5, 2
Socks, 201512, 5, 0
Slippers, 201510, 10, 5
Slippers, 201511, 20, 6
Slippers, 201512, 30, 7
Sandals, 201510, 10, 10
Sandals, 201511, 15, 0
Sandals, 201512, 10, 1

The problem is restated in the attached application. Thanks for taking a look.

[#2]

Either I'm not understanding or it doesn't work. Can you update the app with a working example?

[#3]

I looked into your data and why you have to ignore the Period & months_since_last_sale first place to calculate the avg stock value.

[#4]

Because a single period must be selected -- and the average has to be taken over all periods and (correspondingly) over all months_since_last_sale values.