This paper: The framing and econometrics of child support by Stuart Birks is well worth a read.

Paper for the New Zealand Association of Economists Conference
Wellington, 29 June – 1 July 2011
Abstract
The approach taken to child support in New Zealand has shaped perceptions and outcomes. Despite ongoing dissatisfaction, substantial changes to the legislation have yet to be made. The current Government is considering changes which address some of the major issues: costs of children; incomes of parties; and shared care. IRD analysis replicates an Australian approach to derive a proposed alternative formula. This paper focuses on the importance of framing for shaping perceptions and outcomes, and the way econometrics is playing a part in this process. The analysis may have a wider relevance for the use of economics research.