Collider Bias in Economic History Research

34 Pages Posted: 29 Jun 2020

See all articles by Eric Schneider

Eric Schneider

London School of Economics & Political Science (LSE); Centre for Economic Policy Research (CEPR)

Date Written: June 2020


Economic historians have long been aware that sample-selection bias and other forms of bias could lead to spurious causal inferences. However, our approach to these biases has been muddled at times by dealing with each bias separately and by confusion about the sources of bias and how to mitigate them. This paper shows how the methodology of directed acyclical graphs (DAGs) formulated by Pearl (2009) and particularly the concept of collider bias can provide economic historians with a unified approach to managing a wide range of biases that can distort causal inference. I present ten examples of collider bias drawn from economic history research, focussing mainly on examples where the authors were able to overcome or mitigate the bias. Thus, the paper highlights how to diagnose collider bias and also strategies for managing it. The paper also shows that quasi-random experimental designs are rarely able to overcome collider bias. Although all of these biases were understood by economic historians before, conceptualising them as collider bias will improve economic historians' understanding of the limitations of particular sources and help us develop better research designs in the future.

Keywords: collider bias, directed acyclical graphs, sample-selection bias

JEL Classification: N01, N30

Suggested Citation

Schneider, Eric, Collider Bias in Economic History Research (June 2020). CEPR Discussion Paper No. DP14940, Available at SSRN:

Eric Schneider (Contact Author)

London School of Economics & Political Science (LSE) ( email )

Houghton Street
London, WC2A 2AE
United Kingdom

Centre for Economic Policy Research (CEPR) ( email )

United Kingdom

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