A 2013 economic study by Sarro and Rogers provides some new thinking and new data. See: Mark A. Sarro and R. Mark Rogers, “Economic Review of the Massachusetts Child Support Guidelines,” submitted to the Massachusetts Child Support Guidelines Task Force (June, 2013). Here are some key points from that study:
 “Most states base their child support guidelines, to some extent, on specific economic studies. However, the most widely used studies do not measure actual direct spending on children and are based on national data. Most child costs are not directly observable, but rather are indirect costs shared by adults and children in a household, such as housing and food. Therefore, the available economic data are estimates with theoretical and practical limitations, and the resulting child cost estimates are informative and important to consider, but they are not determinative.” p 1
 “There simply is not a definitive source of data to dictate whether the resulting Guidelines amounts are right or wrong with certainty and in every case. This is why presumptive awards are rebuttable, based on case specific facts that diverge from presumptive facts. The rest of this report summarizes the economic principles, approaches, and most current data available to help inform the Task Force’s review of the current Guidelines.” p. 13
 Income Shares estimates, such as the Betson-Rothbarth amounts, also rely on data from intact (specifically, husband-wife) households to inform policy decisions for households which are not intact. These guideline models implicitly assume economic decisions are made the same way for separate households as for married households, when, in fact, the economic tradeoffs may be very different. One obvious difference is the additional overhead cost required by two separate households relative to the cost of a single household. By failing to account for this additional cost, economic models likely overestimate the standard of living of a non-intact household at a given income level. Maintaining a standard of living estimated based on intact household data likely requires more income than is actually available to a non-intact household.” pp 19-20. Sarro and Rogers show that shared parenting implies higher fixed costs associated with maintaining two households, and that intact families would adjust to such costs.
 Sarro and Rogers (2013) produce detailed data – based on a large random sampling of support orders from several districts within Massachusetts – showing that a large percentage of couples agree to amounts far below Guidelines. These new data raise questions: why any state adopts Guidelines that many consider unreasonable? Why is only one parent presumed to be competent to make spending decisions on behalf of children?