The paper proposes an original class of conditionally heteroskedastic models aimed to capture a new concept of asymmetry. Not only past up and down moves of stock market returns have different impacts on the conditional variance, but also, positive and negative changes are governed by different...

We present an annual sequence of wages in England starting in 1245. We show that a standard AK-type growth model with capital externality and stochastic productivity shocks is unable to explain important features of the data. We then consider random returns to scale. Moderate episodes of...