  When calibrating spatial partial equilibrium models with conjectural
variations, some modelers fit the suppliers' sales to the available data in
addition to total consumption and price levels. While this certainly enhances
the quality of the calibration, it makes it difficult to accommodate
user-imposed bounds on the model parameters such as restricting the market
power parameters to the interval [0,1], which is a common requirement in
conjectural variations approaches. We propose an algorithm to calibrate the
suppliers' sales and simultaneously deal with user-defined bounds on
parameters. To this end, we fix the suppliers' sales at reference values and
obtain the marginal costs for each supplier and market. We then limit the
market power parameters to the interval [0,1], and calculate intervals of
anchor prices and price elasticities that reproduce the reference supplier
sales in the state of equilibrium. If these intervals do not contain the
reference price elasticities and prices, we face a mismatch between reality and
the model mechanics. We resolve this by altering the reference sales for the
critical suppliers, and iterate. Thereby, the user controls whether price
elasticities and anchor prices should be close to their reference values, or
the suppliers' sales. The algorithm is tested on data from the European gas
market, and required less than one minute to identify calibrated parameters.
Our algorithm is widely applicable, since it is based on mild (and common)
underlying assumptions and can be configured to suit a specific purpose thanks
to the inclusion of user-defined bounds on all relevant parameters.
