Practice question · Multiple choice
An economist’s two policy instruments act on two targets through matrix , and . What does this mean for policy?
Hints
- Singular = columns linearly dependent.
- Two levers that are secretly one lever.
Show the answer
D. The instruments are redundant; some targets are unreachable
Why
Zero determinant means the instrument columns are dependent: pulling lever 2 is a disguised multiple of pulling lever 1. The plane of targets collapses to a line, everything off that line is unreachable at any policy strength.
Practise Determinants
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