# Economic consulting internships: analyst work, eligibility, and case interviews

## Separate a common trend from the observed treatment difference

Original fictional exercise: a case team is reviewing average weekly purchases before and after a pricing-policy change in one market. A comparison market did not adopt the policy. The four numbers below are invented and do not establish a causal effect in any real market.

### Fictional before-and-after market comparison

| Market | Before: average weekly purchases | After: average weekly purchases | Policy change |
| --- | --- | --- | --- |
| Market A | 100 | 130 | Yes |
| Market B | 90 | 105 | No |

## Your turn

Calculate the before-to-after change in each market and the simple difference-in-differences estimate. What does that calculation describe, and what additional evidence would you need before calling the policy the cause of the difference?

## Your answer

[Write your approach here.]

## For your own application

Practice one short quantitative example where you calculate the result, name the identifying assumption, and say what additional evidence could overturn your interpretation. That is stronger preparation than memorizing a generic case framework.

Return to the guide for the worked answer and source notes:
https://internshipdeadlines.com/guides/economic-consulting-internship-search