Calculate difference between moving average value of two different dates

[Mr_Glister]

Hi, 

I have daily observations with a bit of variability in their measurements, so I'm calculating a 30 day moving average. 

I do so with the following DAX and it works fine:

My daily weight moving average = 

Smartavgmoving =
VAR _Maxdate = MAX( 'Date table'[Date])
RETURN  CALCULATE( AVERAGE( Table[My daily weight]), DATESBETWEEN( 'Date table'[Date], _Maxdate - 15, _Maxdate +15))

As expected the output looks like this:

I want to calculate the rate of change between certain periods (for example, between every first and last of a month) but no matter how I try to pass a date filter to my moving average calculation, the outcome is always the table above. 

For example, the measure below results in the same table as posted above. 

=CALCULATE( Smartavgmoving, Table[DATE] = dt"2023-01-17"))

Can somebody point me in the right direction?

[amitchandak]

@Mr_Glister , Based on what I got, Try measures like

First of month =
VAR _Maxdate = Eomonth(MAX( 'Date table'[Date]), -1) +1
RETURN CALCULATE( AVERAGE( Table[My daily weight]), DATESBETWEEN( 'Date table'[Date], _Maxdate - 15, _Maxdate +15))

Last of Month=
VAR _Maxdate = Eomonth(MAX( 'Date table'[Date]), 0)
RETURN CALCULATE( AVERAGE( Table[My daily weight]), DATESBETWEEN( 'Date table'[Date], _Maxdate - 15, _Maxdate +15))

[Mr_Glister]

Hi @amitchandak,

(Nice to get help from one of the forum heroes!)

I will try your suggestion and I'm sure it will work for this narrow case. But the real reason I posted this to the forum is the following question:

Since my original measure correctly calculates a value for each date, shouldn't I be able to directly access the values of each date? For example, if - for some reason - I wanted to calculate the difference of exactly the two dates I highlighted. Or put differently, why does the DAX below not work and how would I have to do it correctly?

=CALCULATE( Smartavgmoving, Table[DATE] = dt"2023-01-17"))