The main economic measures that are produced by the model include: (a) total gross margin – including value of home consumed produce, (b) disposable income after household consumption, (c) net cash balances, and (d) the level of accumulated household capital and any outstanding debt balances. These measures are calculated by placing prices on produce outputs and production inputs along with ‘opportunity values’ for home consumption and other non-market uses or disposals of activity outputs (e.g. food crops, residues, manures etc.). Rather than employing an automated optimization strategy, a creep budgeting approach was selected which involves re-specifying various input and output variables in a systematic manner to explore the system response to these changes (Makeham and Malcolm, 1981).