When you make and buy: understanding service delivery portfolios in concurrent sourcing
研究服务交付中自营与外包的分配如何影响绩效，基于英格兰地方政府儿童社会服务数据发现，集中型组合（一种模式主导、另一种辅助）表现更优。
Concurrent sourcing, the simultaneous use of in-house provision and contracting out, remains underexplored. This study examines how the allocation between in-house and contracted modes in service delivery portfolios affects service performance. Using panel data on children’s social care services provided by English local authorities from 2014 to 2023, we find that concentrated portfolios, in which one delivery mode dominates and the other plays a supporting role, are associated with better performance. By contrast, dominant mode itself and the mix of contractor types within outsourced provision show limited influence. The findings highlight portfolio design as central to concurrent sourcing.