Congratulations to Daan Steenkamp, who was awarded the 2017 A. R. Bergstrom Prize in Econometrics for his paper Daan_Steenkamp_dp17-02. The Bergstrom Prize can be awarded every two years and aims to reward the achievement of excellence in econometrics, as evidenced by a research paper in any area of econometrics.

If an asset price contains a ‘bubble’ it will exhibit explosive (i.e. exponential) dynamics. Recently developed tests by Phillips et al. (2015a) and Phillips et al. (2015b) provide an accurate way to gauge whether asset prices are experiencing explosive dynamics, or have done so in the past.

Daan Steenkamp’s paper applies those tests to eleven of the most commonly traded exchange rates at a daily frequency and over a long sample. When measured at a daily frequency, the volatility of exchange rates tends to be high and potentially non-stationary, and there may be a size distortion in the standard tests causing them to over-reject the null that the series is explosive. For this reason, a wild bootstrapping technique is used to compute critical values for statistical interference.

A second contribution of Daan’s paper is to consider the possibility of both positive and negative explosive periods. Currency pairs provide a natural test case in this regard because explosive increases (or collapses) in a foreign currency imply a corresponding collapse (or increase) in the given base currency. Furthermore, the influence of the base currency on the explosive dynamics may be inferred by considering the dynamics of its effective exchange rate, i.e. that currency’s value against a wide basket of foreign currencies.

The results show that bouts of explosiveness in exchange rates against the United States (US) dollar are uncommon at a daily frequency. Periods of explosiveness tend to last for several days but involve only small changes in currency levels. These also usually reverse shortly afterwards.

Second, the dynamics of the US dollar appear to be largely responsible for the results found for the individual currency pairs, as evidenced by a high concordance of their explosiveness with explosiveness in the broad value of the US dollar exchange rate. This result suggests that there are relatively few instances where explosiveness in individual cross-rates reflected country-specific factors. There is also evidence that explosive episodes in currency markets coincide with periods of high market volatility.

In their assessment, the adjudicators Professors Mark Holmes and Bob Reed noted that Daan’s work was “competent analysis based on cutting edge econometric techniques that provide valuable insights.”