Consider a difference-in-difference model of job lock. The research fi nds the following probabilities:

The Probability of Changing Jobs Employer-Provided Health Insurance No No other health insurance Other health insurance 0.15 0.25 Yes 0.10 0.24

(a) Interpret each element of this matrix in terms of the probability of changing jobs.

(b) Does the presence of alternative insurance mitigate job lock? Explain your answer.

(c) Does the difference-in-difference calculation validate the larger impact of “other insurance” found by Madrian? Why or why not?
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