Policymakers and scholars have long proposed that willingness to participate in armed conflict is influenced by citizens' income-earning opportunities. Testing this opportunity cost mechanism has led to mixed results. One reason for this might be the fact that current proxies can also serve as indicators to test grievance-based theories. In this study, we construct a more suitable measure. We use crop calendars and crop location data to build an index of agricultural idle time for first administration units on the African continent from 1990 to 2017. We test the explanatory power of this measure by examining its relationship with armed conflict. Our results show that agricultural idle time increases the probability of observing armed conflict by more than 20 percent.

This paper proposes a Bayesian multilevel spatio-temporal model with a time-varying spatial autoregressive coefficient to estimate temporally heterogeneous network interdependence. To tackle the classic reflection problem, we use multiple factors to control for confounding caused by latent homophily and common exposures. We develop a Markov Chain Monte Carlo algorithm to estimate parameters and adopt Bayesian shrinkage to determine the number of factors. Tests on simulated and empirical data show that the proposed model improves identification of network interdependence and is robust to misspecification. Our method is applicable to various types of networks and provides a simpler and more flexible alternative to coevolution models.

When working with panel data, many researchers wish to estimate the direct effects of time-varying factors on future outcomes. However, when a baseline treatment affects both the confounders of further stages of the treatment and the outcome, the estimation of controlled direct effects (CDEs) using traditional regression methods faces a bias trade-off between confounding bias and post-treatment control. Drawing on research from the field of epidemiology, in this article I present a marginal structural modeling (MSM) approach that allows scholars to generate unbiased estimates of CDEs. Further, I detail the characteristics and implementation of MSMs, compare the performance of this approach under different conditions, and discuss and assess practical challenges when conducting them. After presenting the method, I apply MSMs to estimate the effect of wealth in childhood on political participation, highlighting the improvement in terms of bias relative to traditional regression models. The analysis shows that MSMs improve our understanding of causal mechanisms especially when dealing with multi-categorical time-varying treatments and non-continuous outcomes.