The Australian electricity market’s pre-dispatch process: Some observations on its efficiency using ordered probit model

Many market participants in Australia Electricity Market had cast doubts on whether the pre-dispatch process in the electricity market is able to give them good and timely quantity and price information. In a study by [11], they observed a significant bias (mainly indicating that the pre-dispatch process tends to underestimate spot price outcomes), a seasonality features of the bias across seasons and/or trading periods and changes in bias across the years in our sample period (1999 to 2007). In a formal setting of an ordered probit model we establish that there are some exogenous variables that are able to explain increased probabilities of over-or under-predictions of the spot price. It transpires that meteorological data, expected pre-dispatch prices and information on past over-and under-predictions contribute significantly to explaining variation in the probabilities for over-and under-predictions. The results allow us to conjecture that some of the bids and re-bids provided by electricity generators are not made in good faith.