Comparison of Effects from Different Institutions: Public Credit Guarantee in Korea*

We aim to compare the activities of the two main credit guarantee institutions in Korea. There has been mounting criticism that although these institutions were mandated to play different roles in financing small and medium‐sized enterprises (SME), their operations are, in fact, similar, and many SME receive overlapping support from both institutions. Using the propensity score matching method (allowing for multiple, mutually exclusive support scenarios) to compare the effects of PCG on different institutions, the present study provides suggestions to help the government make decisions regarding the consolidation of PCG funds. The results suggest that the institutions function differently and target different SME. However, overlapping support enables firms to expand their sales only, indicating the existence of inefficiency in the case of overlapping support to firms.     

Impact of metal silos on households’ maize storage,storage losses and food security: An application of a propensity score matching

Maize is the most important food staple in Eastern and Southern Africa, with a highly seasonal production but relatively constant consumption over the year. Farmers have to store maize to bridge seasons, for food security and to protect against price fluctuations. However, the traditional storage methods do not protect grain well, resulting in large postharvest losses. Hermetically sealed metal silos kill storage pests by oxygen deprivation without pesticides. Popular in Central America, they are now being promoted in Africa, but their impact here has not yet been studied. This study used propensity score matching to evaluate the impact of metal silos on duration of maize storage, loss abatement, cost of storage, and household food security. Metal silo adopters (N = 116) were matched with non-adopting farmers from a representative sample of 1340 households covering the major maize-growing zones in Kenya. The major effect of the metal silos was an almost complete elimination of losses due to insect pests, saving farmers an average of 150–200 kg of grain, worth KSh9750 (US$130). Metal silo adopters also spent about KSh340 less on storage insecticides. Adopters were able to store their maize for 1.8–2.4 months longer, and to sell their surplus after five months at good prices, instead of having to sell right after the harvest. The period of inadequate food provision among adopters was reduced by more than one month. We conclude that metal silos are effective in reducing grain losses due to maize-storage insects, and that they have a large impact on the welfare and food security of farm households. The initial cost of metal silos is high (KSh20,000/1.8 ton) and therefore policies to increase access to credit, to reduce the cost of sheet metal, and to promote collective action can improve their uptake by smallholder farmers.     

An evaluation of government- sponsored vocational training programmes for the unemployed in urban Russia

This is the first study on the effects of active labour marketprograms such as training in Russia. We use the data from theofficial unemployment register combined with information fromthe follow-up survey in a large industrial city in the year2000. The method of propensity score matching was applied tolearn whether participation in the training programmes increasedthe monthly salaries of participants. The findings suggest thatindividuals tend to benefit from the participation in the trainingprogrammes. However, one year later, this effect disappeared.     

Is There Persistence in the Impact of Emergency Food Aid? Evidence on Consumption, Food Security, and Assets in Rural Ethiopia

We identify the impact of emergency food aid programs after the 2002 drought in rural Ethiopia on future welfare. Based on a difference-in-differences matching estimator, participation in food-for-work increases growth in total consumption and food consumption eighteen months after the drought. Separately, receiving free food raises growth in food consumption, but, surprisingly, negatively impacts food security. Food-for-work benefited households in the middle and upper tail of the consumption distribution, while the better-targeted free food program benefited the poorest. Evidence suggests these impacts demonstrate accumulated and persistent effects of food aid received in the first twelve months after the drought.     

土地流转对农户贫困脆弱性的影响研究

研究目的:探究土地流转对农户贫困脆弱性的影响,为防范农户陷入贫困和解决农村贫困提供理论和实证依据。研究方法:本文借助2016年湖北省1682个农户实地调查数据,基于倾向得分匹配法(PSM)和回归方程的Shapley值分解法,分别考察国定贫困线、1.9美元贫困线和3.1美元贫困线下不同类型土地有无转出和转出面积对农户贫困脆弱性的影响。研究结果:土地转出能够显著降低农户的贫困脆弱性,且农户贫困脆弱性随着转出土地面积的增加而降低;从土地转出的异质性来看,水田转出对缓解农户贫困脆弱性的效果更为明显,旱地转出的效果次之。研究结论:应进一步加快农村土地流转,释放农村剩余劳动力,不断增加农户收入,从而降低农户贫困脆弱性。     

Scoring rules and survey density forecasts

This article provides a practical evaluation of some leading density forecast scoring rules in the context of forecast surveys. We analyse the density forecasts of UK inflation obtained from the Bank of England’s Survey of External Forecasters, considering both the survey average forecasts published in the Bank’s quarterly Inflation Report, and the individual survey responses recently made available to researchers by the Bank. The density forecasts are collected in histogram format, and the ranked probability score (RPS) is shown to have clear advantages over other scoring rules. Missing observations are a feature of forecast surveys, and we introduce an adjustment to the RPS, based on the Yates decomposition, to improve its comparative measurement of forecaster performance in the face of differential non-response. The new measure, denoted RPS*, is recommended to analysts of forecast surveys.     

连续批计数抽样检验中的跳批抽样技术

文章介绍了跳批抽样的基本原理、适用范围、条件以及一般程序。文章主要对GB／T2828．3《计数抽样检验程序第3部分跳批抽样程序》技术内容进行了解读和介绍,帮助实际应用者正确运用跳批抽样程序,以达到预期目的。     

新一轮退耕还林对农户收入影响的机理研究 ——基于赣南、鄂北农户调查的实证分析

研究目的：新一轮退耕还林补助资金即将到期之际,分析新一轮退耕还林对农户家庭收入的净效应并揭示其内在机制。研究方法：理论上阐述了新一轮退耕还林政策促进农户收入增长的作用机理,基于赣南、鄂北地区农户调查数据,利用倾向得分匹配法进行实证分析。研究结果：（1）无论是否包含退耕补贴,新一轮退耕还林政策对农户收入有正向影响;（2）退耕林种对农户收入的作用机理不同：种植经济林的农户增加了林果业收入和非农经营收入,减少了工资性收入;种植生态林的农户通过提高工资性收入,进而提高总收入水平。研究结论：新一轮退耕还林加快了农户生计转型的进程。政策实施5年后,农户形成与生态环境相适应且稳定的生产方式,为补偿政策的逐步退出创造有利条件,实现了新一轮退耕还林政策的造血功能。     

THE ESTIMATED EFFECT OF CATHOLIC SCHOOLING ON EDUCATIONAL OUTCOMES USING PROPENSITY SCORE MATCHING

This paper examines the effect of attending a Catholic high school on educational outcomes. The statistical analysis is based on data obtained from the US National Educational Longitudinal Study. Using propensity score matching methods to control for selection bias, we find that Catholic schooling improves maths test scores, with stronger effects for males than for females, but appears to have little effect (if any) on reading scores. Catholic schooling also raises high school graduation rates and substantially increases the likelihood of enrolment in a 4‐year college. Use of the difference‐in‐difference method suggests that the effect of Catholic schooling on changes in maths scores is more muted, though still statistically significant.     

Parametric Robust Test for Several Variances with Unknown Underlying Distributions

Tsou (in comm Stat-Theor Math 32: 2013–2019, 2003) proposed a parametric robust procedure for testing the equality of two population variances. With large samples the proposed test remains valid under model misspecification. In this article the robust technique is further extended to the comparison of several population variances. More specifically the score test derived on the basis of normal models is adjusted to become robust. The adjusted robust test provides asymptotically valid inference so long as the true underlying distributions have finite fourth moments. Unlike most robust nonparametric approaches, this novel robust technique too provides legitimate variance estimates for estimators of the interested parameters.