ScotCET and causal mediation analysis with a single mediator 3. – A demonstration in R

This post finishes the discussion of two other ones (this and this) by providing an example how to carry out causal mediation analysis with a single mediator in R. The “mediation” package is utilised, for a full description of the package’s capabilities, you can refer to Tingley et al. (2014). For STATA users out there, there is a “paramed” package in STATA which should also produce the same results (within rounding error). A note of caution though: the “paramed” package can only be used with linear mediators and outcomes, and with binary logit models with rare outcomes (see: VanderWeele 2016). The dataset for the analysis can be downloaded from the bottom of the page. Continue reading “ScotCET and causal mediation analysis with a single mediator 3. – A demonstration in R”

ScotCET and causal mediation analysis with a single mediator 2. – Issues with the product method and the sequential ignorability assumption

As discussed in this earlier post, to make meaningful inference from the ScotCET dataset, the focus needs to be shifted to the mediated effect. In such cases, following Baron and Kenny’s (1986) influential article, social scientists usually rely on structural equation modelling and the product method to derive the direct and indirect effects. Nevertheless, this approach has serious limitations that are usually overlooked in the applied literature. Continue reading “ScotCET and causal mediation analysis with a single mediator 2. – Issues with the product method and the sequential ignorability assumption”

ScotCET and causal mediation analysis with a single mediator 1. – Procedural justice and normative alignment with the police

This post continues the discussion of the Scottish Community Engagement Trial (ScotCET). In four posts (you can find them here, here, here, and here) I discussed the apparent failure of implementation over the summer. I concluded that despite the unexpected direction of the findings (i.e., those who received the procedurally just treatment had more negative opinion of the police), the treatment effect appeared to be consistent, was not heterogeneous, and thus it could be actually attributed to the research design. Continue reading “ScotCET and causal mediation analysis with a single mediator 1. – Procedural justice and normative alignment with the police”