Dynamic result KPI selection

[domibs]

Hello, I've created the below KPI calculation to get the variation between the first price et the last price : 

((LastValue("Price"))-(FirstValue("Price")))/(FirstValue("Price"))

The calculation works but when I filter on month (field "[Year month]"),  the result of the KPI calculation does not change with the selection. 

For exemple : 

Reference	Year month	Price
123990	2020-10	2,85 €
123990	2020-12	2,85 €
123990	2021-04	2,95 €
123990	2021-10	3,25 €
123990	2022-03	3,35 €
123990	2022-04	3,70 €

The variation between the last price and the first price in this table is 29,82% ((3,70-2,85)/2,85).

If I filter only on few months, I get the below table. And the result of the KPI calculation should be : 13,85% ((3,70-3,25/3,25).

Reference	Year month	Price
123990	2021-10	3,25 €
123990	2022-03	3,35 €
123990	2022-04	3,70 €

However, the result does not change with the month selection in my Qlik application. 

Could you please help me to find the solution ? 

Thank you,

Have a great day,

[Angela_Zhou]

How about,

(firstsortedvalue(Price, -[Year month]) - firstsortedvalue(Price, [Year month]))
/
firstsortedvalue(Price, [Year month])

Here, for any selected [Year month] with assumption of this field can be sorted in ASC order by year + month, then:

• firstsortedvalue(Price, [Year month]) = the price of oldest year+month 
• firstsortedvalue(Price, -[Year month]) = the price of most recent year+month (pay attention to the negative sign)