本稿では，個別事例の因果推論におけるSynthetic Control Method（SCM）の利用可能性を検討する．SCMは処置前の結果変数と共変量で処置を受けた主体と一致するように，対照群を適当な重みづけから統合したsynthetic controlを構築し，このsynthetic controlと処置群との比較から個別主体の因果効果の識別を行う．本稿ではSCMのアプリケーションとして，阪神淡路大震災が貧困層拡大へ与える影響を検討した．分析の結果，震災発生後にラグ期間を伴って生活保護後受給者数は増加し，震災発生から15年たっても，震災効果が持続することが示された．本稿ではさらに，推定のパフォーマンスの観点からSCMのオルタナティブとなる差の差（Difference-in-Differences，DD）分析との比較を，実データ，およびモンテカルロ・シミュレーションを用いて行った．結果として，主体毎に異なる時間的トレンドが存在しない場合には，SCMとDDは同様の推定値を導くが，主体毎に異なる時間的トレンドが存在する場合は，SCMの方がバイアスの少ない推定量であることが示された．これらの結果は，個別主体の因果推論において，とくに未知の時間的トレンドが存在する場合に，SCMが適した推定手法であることを示している．
The purpose of this study is to build a Bayesian model for the income distribution generating process. Mathematical models of income distribution have been developed in the social sciences field; however, these models lack empirical validity. Human capital approaches have been developed to estimate the effect of individual investment on earnings, but those approaches lack rigorous mathematical consistency with the probability distribution of income. There is no appropriate probability model for testing the empirical validity of the theory that can explain the genesis of the distribution through human capital. To solve the problem, we built a generative income distribution model, expressed as a stochastic model, which formally represents human capital theory and a rigorous micro-macro linkage. Using nationwide survey data in Japan, we estimate the posterior distributions of the parameters of the probabilistic toy model using Markov chain Monte Carlo method. Moreover, we try to check the predictive accuracy of the models using the widely appreciable information criteria and the leave-one-out cross-validation. As a result, we conjecture that the predictive accuracy of the theory-based model is as good as that of the generalized linear model and provides interesting information about latent parameters.
Japan is experiencing the depopulation of many rural areas due to the outmigration of younger residents, who seek higher wages than those accrued from local small- and medium-sized enterprises (SMEs). However, some rural residents appear to be relatively satisfied with their daily lives. Few studies have investigated variations among young residents’ attitudes toward their jobs and personal lives and willingness to remain living in or leave their residential rural areas. This study used open interviews with a group of rural SME workers as the basis for the creation and administration of social surveys among a sample of 220 young workers in Iide, Yamagata Prefecture, Northern Japan. Analyses of the survey results demonstrated that although most respondents were dissatisfied with their work salaries and positions, they expressed satisfaction with their residential communities. Participants who were more willing to remain in their residential rural area had a higher satisfaction from their leisure and progress at work, but also reported a lower satisfaction from their coworkers. Rural SMEs can retain more young workers in rural areas by ensuring a better work-life balance and empowering employees with a greater sense of responsibility.