Balancing bias and variance in the design of behavioral studies: The importance of careful measurement in randomized experiments

Andrew Gelman.
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The Centre for Central Banking Studies recently hosted their annual Chief Economists Workshop, whose theme was “What can policymakers learn from other disciplines”.  In this guest post, one of the keynote speakers at the event, Andrew Gelman professor of statistics and political science at Columbia University, points out some of the pitfalls of randomly assigned experiments with control groups.

When studying the effects of interventions on individual behavior, the experimental research template is typically:  Gather a bunch of people who are willing to participate in an experiment, randomly divide them into two groups, assign one treatment to group A and the other to group B, then measure the outcomes.  If you want to increase precision, do a pre-test measurement on everyone and use that as a control variable in your regression.  But in this post I argue for an alternative approach- study individual subjects using repeated measures of performance, with each one serving as their own control.

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If Pate’s Grammar School set UK Monetary Policy…

Samuel Cole, Jack Sherer-Clarke, Oliver Wallbridge, Annabel Manley.

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Each year, the Bank of England organises the Target 2.0 competition for A-level economics students. In this guest post, the winning team at March’s national final from Pate’s Grammar School explain what they would do if they were the MPC…

We decided as a team to hold the Bank Rate at 0.5% and to maintain asset purchases at £375bn. In our view it is not yet time to tighten monetary policy. Though we believe the output gap is small, the economy is yet to reach escape velocity and the Wicksellian natural rate of interest is likely to remain depressed. We are more optimistic on potential supply than other economists and think oil prices will stay low. As such, we predicted that inflation will only reach 1.7% in 2018Q1 compared to the MPC’s median forecast in February of around 2.1% (which has since fallen to 1.9%).

Continue reading “If Pate’s Grammar School set UK Monetary Policy…”