Identification of equations explaining a continuous variable, e.g., the length of sickness absence spells, by age, cohort and time (ACT), subject to their definitional identity is reconsidered. Various extensions of a linear equation to polynomials are explored. If no interactions between the...

We analyse retailer and household behaviour on the Norwegian electricity market, based on detailed information on prices and other market characteristics. We find that there exists a competitive market segment where a number of retailers compete fiercely for customers, with small margins on all...