Help Calculating School Performance Index in Power BI (Complicated Calculation in Power BI)

[rachaellearns]

Hi Friends, 

I am trying to calculate a school and district's "Performance Index" in Power BI. 

1) Calculate the percentage of tests in each subject that fall into a given performance level (limited, proficient, advanced).

2)Assign points based on the percentage of tests in each performance level. (For example, advanced is worth 2 points, proficient is worth 1, and limited is worth 0.5. A school with 50% of students in the Limited category, 30% of students in the Proficient category, and 20% of students in the Advanced category would earn 95 points, because (50 x 0.5)+(30 x 1) + (20 x 2) = 95 points.)

My data is formatted as follows 

student_id	subject	school_year	performance_level
1234	Math	2022	Limited
1234	Reading	2022	Proficient
5678	Math	2022	Advanced
5678	Reading	2022	Proficient
1357	Math	2022	Limited
1357	Reading	2022	Limited

There will be multiple school years in this file as well - this is a simplified view. 

How would I approach this in Power BI? Would it be best to do this in PowerQuery somehow, or would it be better to create a measure in DAX? A mixture of both? 

PowerBI is not something I frequently use and am very much a beginner, so I appreciate any help you can provide!

[v-cgao-msft · Accepted solution]

Hi @rachaellearns ,

Please new two measures:

percentage = 
VAR _count = COUNTROWS('Table') + 0
VAR _total = CALCULATE(COUNTROWS('Table'),ALLEXCEPT('Table','Table'[subject],'Table'[school_year]))
VAR _percentage = DIVIDE(_count,_total)
RETURN
_percentage

points = 
VAR _subject= MAX('Table'[subject])
VAR _year = MAX('Table'[school_year])
VAR _Advanced = SUMX(FILTER('Table','Table'[subject]=_subject&&'Table'[school_year]=_year&&'Table'[performance_level]="Advanced"),[percentage])+0
VAR _Proficient = SUMX(FILTER('Table','Table'[subject]=_subject&&'Table'[school_year]=_year&&'Table'[performance_level]="Proficient"),[percentage])+0
VAR _Limited = SUMX(FILTER('Table','Table'[subject]=_subject&&'Table'[school_year]=_year&&'Table'[performance_level]="Limited"),[percentage])+0
VAR _Point = (_Advanced*2+_Proficient+_Limited*0.5)*100
RETURN
_Point

M or DAX? That is the Question

KNP's answer:

When should I favor DAX over PowerQuery for perfor...

Comparing DAX calculated columns with Power Query computed columns

Best Regards,
Gao
Community Support Team

If there is any post helps, then please consider Accept it as the solution  to help the other members find it more quickly. If I misunderstand your needs or you still have problems on it, please feel free to let us know. Thanks a lot!

How to get your questions answered quickly -- How to provide sample data

[rachaellearns]

Wow, thank you so much for the help with this! I do have one question -- what is the reason for adding a zero at the end of the SUMX calculations? Is it so it doesn't return an error in the case of a null/blank value?

[aj1973]

Hi @rachaellearns 

Power Query is best for ETL, DAX is best for calculations.