农民工大规模外出的经济增长效应研究

农民工大规模外出的影响和作用十分复杂.利用反设事实法,并运用Cobb-Douglas生产函数,分析了湖南省2001-2011年经济增长过程中资本投入、劳动投入和技术进步的贡献,并对于湖南省2001-2011年潜在经济增长进行了进一步推断.研究结果:如果不存在出省打工的数百万农民工,同期湖南将实现净增长428％,年均经济增长率18.10％,比现实经济增长率高出0.5个百分点.这表明农民工大规模外出尽管带来了可观的劳务收入,但也使得流出地区实际经济总量低于其可能的潜在总量,导致其实际经济增长率低于其潜在经济增长率,从而也间接证明了农民工大规模出省打工对于农民工流出地区的经济增长具有一定抑制作用.地方政府在将发展“劳务经济”作为发展战略的同时,还应认识到,“劳务经济”发展战略在带来较多劳务收入的同时,也会在一定程度上削弱地方社会经济的发展潜力.当前不宜将农村剩余劳动力转移作为对各级地方政府目标责任考核内容.     

Importance of Baseline Specification in Evaluating Conservation Interventions and Achieving No Net Loss of Biodiversity

There is an urgent need to improve the evaluation of conservation interventions. This requires specifying an objective and a frame of reference from which to measure performance. Reference frames can be baselines (i.e., known biodiversity at a fixed point in history) or counterfactuals (i.e., a scenario that would have occurred without the intervention). Biodiversity offsets are interventions with the objective of no net loss of biodiversity (NNL). We used biodiversity offsets to analyze the effects of the choice of reference frame on whether interventions met stated objectives. We developed 2 models to investigate the implications of setting different frames of reference in regions subject to various biodiversity trends and anthropogenic impacts. First, a general analytic model evaluated offsets against a range of baseline and counterfactual specifications. Second, a simulation model then replicated these results with a complex real world case study: native grassland offsets in Melbourne, Australia. Both models showed that achieving NNL depended upon the interaction between reference frame and background biodiversity trends. With a baseline, offsets were less likely to achieve NNL where biodiversity was decreasing than where biodiversity was stable or increasing. With a no‐development counterfactual, however, NNL was achievable only where biodiversity was declining. Otherwise, preventing development was better for biodiversity. Uncertainty about compliance was a stronger determinant of success than uncertainty in underlying biodiversity trends. When only development and offset locations were considered, offsets sometimes resulted in NNL, but not across an entire region. Choice of reference frame determined feasibility and effort required to attain objectives when designing and evaluating biodiversity offset schemes. We argue the choice is thus of fundamental importance for conservation policy. Our results shed light on situations in which biodiversity offsets may be an inappropriate policy instrument Importancia de la Especificación de Línea de Base en la Evaluación de Intervenciones de Conservación y la Obtención de Ninguna Pérdida Neta de la Biodiversidad