Re-testing Prebisch–Singer hypothesis: new evidence using Fourier quantile unit root test

The Prebisch–Singer hypothesis in economics asserts that over time the relative price of primary goods relative to manufactured goods should experience a downward trend. To test the hypothesis, we must first establish the unit root properties of the relative price term and then regress the stationary series on a trend term. We use the quantile unit root test which allows for both smooth unknown numbers and the form of breaks in the trend function through a Fourier function to show that the relative price of 23 out of 24 primary goods is stationary. However, the Prebisch–Singer hypothesis is supported only in half of the primary commodities.