The "where did votes go" analysis estimates flows from one party to another between two consecutive cycles at the multi-mandate region level. This page documents the statistical method behind the estimates.
What this page covers
Non-negative least squares (NNLS) Goodman regression at the section level.
RAS scaling, which forces the row and column sums of the transition matrix to match observed totals.
Why "small parties" and abstainers are included as their own categories.
When the method misleads — sections with few voters, demographic change, newly registered voters.
See also Voter persistence, which uses the same method to measure party loyalty.