Determining how many of base (user selected) exist in comparison (user selected) - powerbi

Question

I want to be able to show what % of the students that were registered in the base term (in selected major) were also registered in the comparison term. Base term and comparison term would be selected by user with slicers.
My data is:
StudentID
Term
Major
12345
Fall21
History
12345
Spring22
English
11111
Fall21
History
22222
Spring22
English
33333
Fall21
Accounting
I'd like to show the number of students in the base term with that major and the percentage of those students that were also in the comparison term regardless of major. So, if base=Fall21, comparison=Spring22, and major=history, then 2 students were registered in base term as History and of them, only 1 returned (I don't care about their subsequent major) for a return rate of 50%.
I've tried:
returners =
VAR base=min(baseterm[Term]) #this is a separate table that the slicer selects on# VAR comp=min(compterm[Term]) #this is a seperate table that the other slicer selects on# RETURN CALCULATE (DISTINCTCOUNT (registration[studentid]), FILTER (registration, registration[Term] = base || registration[Term] = comp))
but that just pulls either term. I've also tried... RETURN CALCULATE (DISTINCTCOUNT (registration[studentid]), FILTER (registration, registration[Term] = base && registration[Term] = comp))
but it returns no values. Given that I can't even get the students and term portion to work, I haven't been able to work out how to include the major.

Answer 1

Try the following measure:
=
VAR SelectedBaseTerm =
MIN( baseterm[Term] )
VAR SelectedCompTerm =
MIN( compterm[Term] )
VAR T1 =
SELECTCOLUMNS(
FILTER( registration, registration[Term] = SelectedBaseTerm ),
"ID", registration[StudentID]
)
VAR RegisteredinBaseTerm =
COUNTROWS( T1 )
VAR RegisteredinCompTerm =
COUNTROWS(
FILTER(
ALL( registration ),
registration[Term] = SelectedCompTerm
&& registration[StudentID] IN T1
)
)
RETURN
DIVIDE( RegisteredinCompTerm, RegisteredinBaseTerm )