In their full research article, Belinda Archibong and Nonso Obikili use an instrumental variables approach to establishing the causal effect of colonial imprisonment on trust in legal institutions. Their instrument is the product of a region$$s suitability of palm oil cultivation $(1=$ suitable, $0=$ not suitable$)$ and the region$$s having received good rainfall between $1920$ and $1938(1=$ good, $0=$ bad$).$