Via email, a comment on my comments about the difficulty of settling questions about the Phillips curve empirically:
Dear Professor Thoma,
I saw your recent post on the difficulty of empirically testing the Phillips Curve, and I just wanted to alert you to a survey paper on this topic that I wrote with Sophocles Mavroeidis and Jim Stock: "Empirical Evidence on Inflation Expectations in the New Keynesian Phillips Curve". It was published in the Journal of Economic Literature earlier this year (ungated working paper).
In the paper we estimate a vast number of specifications of the New Keynesian Phillips Curve (NKPC) on a common U.S. data set. The specification choices include the data series, inflation lag length, sample period, estimator, and so on. A subset of the specifications amount to traditional backward-looking (adaptive expectation) Phillips Curves. We are particularly interested in two key parameters: the extent to which price expectations are forward-looking, and the slope of the curve (how responsive inflation is to real economic activity).
Our meta-analysis finds that essentially any desired parameter estimates can be generated by some reasonable-sounding specification. That is, estimation of the NKPC is subject to enormous specification uncertainty. This is consistent with the range of estimates reported in the literature. Even if one were to somehow decide on a given specification, the uncertainty surrounding the parameter estimates is typically large. We give theoretical explanations for these empirical findings in the paper. To be clear: Our results do not reject the validity of the NKPC (or more generally, the presence of a short-run inflation/output trade-off), but traditional aggregate time series analysis is just not very informative about the nature of inflation dynamics.
PhD candidate in economics, Harvard University