How to create chain index USING dax? - powerbi

Question

I have a table with department, category, year and sales. See the sample table below:
Table name: ABC
department
category
year
sales
Finance
1
2012
20
HR
1
2012
30
Marketing
1
2012
60
Finance
2
2012
50
HR
2
2012
15
Marketing
2
2012
17
Finance
1
2013
60
HR
1
2013
40
Marketing
1
2013
90
Finance
2
2013
7
HR
2
2013
20
Marketing
2
2013
22
Finance
1
2014
50
HR
1
2014
39
Marketing
1
2014
120
Using the DAX query language, I was able to create the relative index
department
category
year
sales
relative_index
Finance
1
2012
20
100
HR
1
2012
30
100
Marketing
1
2012
60
100
Finance
2
2012
50
100
HR
2
2012
15
100
Marketing
2
2012
17
100
Finance
1
2013
60
(60/20)*100 = 300
HR
1
2013
40
(40/30)*100 = 133
Marketing
1
2013
90
(90/60)*100 = 150
Finance
2
2013
7
(7/50)*100 = 14
HR
2
2013
20
(20/15)*100 = 133
Marketing
2
2013
22
(22/17)*100 = 129
Finance
1
2014
50
(50/60)*100 = 83
HR
1
2014
39
(39/40)*100 = 97.5
Marketing
1
2014
120
(120/90)*100 = 133
I used the following dax code to create the relatie_index
Relative_Link =
//Inception = get the minimum year
var Inception = MIN(ABC[year])
//FY_LY = get the previous year
var FY_LY = ABC[year]-1
//LY_level = get the previous year's sales for a department and category
previous year
var LY_level = calculate(sum(ABC[sales]), filter(allexcept(ABC, ABC[department],
ABC[category]), ABC[year]=FY_LY))
return if(ABC[year]=Inception, 100, (ABC[sales]/LY_level)*100)
I am having trouble creating the chain_index column
department
category
year
sales
relative_index
chain_index
Finance
1
2012
20
100
100
HR
1
2012
30
100
100
Marketing
1
2012
60
100
100
Finance
2
2012
50
100
100
HR
2
2012
15
100
100
Marketing
2
2012
17
100
100
Finance
1
2013
60
(60/20)*100 = 300
(100*300)/100 = 300
HR
1
2013
40
(40/30)*100 = 133
(100*133)/100 = 133
Marketing
1
2013
90
(90/60)*100 = 150
(100*150)/100 = 150
Finance
2
2013
7
(7/50)*100 = 14
(100*14)/100 = 14
HR
2
2013
20
(20/15)*100 = 133
(100*133)/100 = 133
Marketing
2
2013
22
(22/17)*100 = 129
(100*129)/100 = 129
Finance
1
2014
50
(50/60)*100 = 83
(83*300)/100 = 249
HR
1
2014
39
(39/40)*100 = 97.5
(97.5*133)/100 = 130
Marketing
1
2014
120
(120/90)*100 = 133
(133*150)/100 = 199.5
I am trying to use the following formula:
Chain_Index =
//Inception = get the min year
var Inception = MIN(ABC[year])
//FY_LY = get the previous year
var FY_LY = ABC[year]-1
//Next_Year = Inception + 1
var next_year = Inception + 1
//LY_ChainIndex_Value = get the previous chain index value from previous year
var LY_ChainIndex_Value = calculate(sum(ABC[chain_index]), filter(allexcept(ABC,
ABC[department], ABC[category]), ABC[FY_CY]=FY_LY))
return if(ABC[FY_CY]=Inception, 100, (ABC[relative_index]*LY_ChainIndex_Value)/100)
I am getting the following error message:
A circular dependency was detected: ABC[chain_index].
I am trying to create chain index value described in this youtube video:
https://www.youtube.com/watch?v=TXzNvxCB0_g&t=234
Thanks for reading and help will be appreciated

Answer 1

After some quick testing, the following column works great to calculate the chain_index:
chain_index =
VAR _ly = [year] - 1
VAR _ly_index =
CALCULATE (
SUM ( 'ABC'[relative_index] ) ,
ALLEXCEPT ( 'ABC' , 'ABC'[department] , 'ABC'[category] ) ,
'ABC'[year] = _ly
)
RETURN
IF (
ISBLANK ( _ly_index ) ,
100 ,
( [relative_index] * _ly_index ) / 100
)
Basing the relative_index on the following:
relative_index =
VAR _ly = [year] - 1
VAR _ly_sales =
CALCULATE (
SUM ( 'ABC'[sales] ) ,
ALLEXCEPT ( 'ABC' , 'ABC'[department] , 'ABC'[category] ) ,
'ABC'[year] = _ly
)
RETURN
IF (
ISBLANK ( _ly_sales ) ,
100 ,
100.0 * ( [sales] / _ly_sales )
)
I suspect the circular dependency is caused by whatever it is you are doing to calculate this column 'ABC'[FY_CY] - a column you do not need for this calculation at least.
Unless you are planning to deploy these indexing columns for categorization or slicing, then the best practice is to calculate these values using measures instead of making your data model bigger with calculated columns.