Question

A 2021 paper by Callaway and Sant’Anna proposed a variant of this technique to avoid a problematic “two-way fixed effect” specification for “staggered” designs. The “Ashenfelter dip” raises problems for this technique if it is unknown whether a shock is permanent or transitory. A 2004 paper by Marianne Bertrand et al. that asks “How Much Should We Trust [this technique]” simulates inconsistent standard errors using “placebo laws.” A key assumption underlying this technique is the presence of parallel trends in the pre-period. (10[1])Card and Krueger used this technique to study the (10[1])effect of an increase in minimum wages on employment in Pennsylvania. For 10 points, name this causal inference technique that compares the change in an outcome variable over time between treatment and control groups. ■END■ (0[7])

ANSWER: difference-in-differences [accept diff-diff or DID or DD; prompt on causal inference until read; prompt on regression; prompt on natural experiment or longitudinal study by asking “analyzed using what econometric technique?”]
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PlayerTeamOpponentBuzz PositionValue
Ivvone Zhou (UG)UNC B (UG)UNC C (UG)8110
Caleb Kendrick (Grad)Maryland A (Grad)UNC A (Grad)9010
Kevin Jiang (UG)Duke A (UG)GWU B (Grad)1250
Dixie Lumsden (DII)Roanoke College A (DII)Liberty C (DII)1250
Andrew Storm (DII)GWU B (Grad)Duke A (UG)1250
Meredie Cohen (DII)William & Mary A (UG)GWU A (UG)1250
Ethan Cohen (UG)GWU A (UG)William & Mary A (UG)1250
Derek Works (DII)Liberty B (DII)Maryland C (DII)1250
Nathan Redford (DII)Liberty C (DII)Roanoke College A (DII)1250