Direct replication

Definition: As ‘direct replication’ does not have a widely-agreed technical meaning nor there is no clear cut distinction between a direct and conceptual replication, below we list several contributions towards a consensus. Rather than debating the ‘exactness’ of a replication, it is more helpful to discuss the relevant differences between a replication and its target, and their implications for the reliability and generality of the target’s results. Generally, direct replication refers to a new data collection that attempts to replicate original studies’ methods as closely as possible. A replication attempt that “seek(s) to duplicate the necessary elements that produced the original finding.” (Cruwell et al., 2019; p.243). The purpose of a direct replication can be to identify type 1 errors and/or experimenter effects, determine the replicability of an effect using the same or improved practices, or to create more specific estimates of effect size (Hűffmeier et al., 2016). Directness of replication is a continuum between repeating specific observations (data) and observing generalised effects (phenomena). How closely a replication replicates an original study is often a matter for debate, often with differences being cited as hidden moderators of effects. Furthermore, there can be debate over the relevant importance of technical equivalence (i.e., using identical materials) versus psychological equivalence (i.e., realizing the identical psychological conditions) to the original study (Schwarz and Strack, 2014). For example, consider a study on Trust in the US- President conducted in 2018. A technical equivalent replication would use Trump as stimulus (he was president in 2018) a psychological equivalent study would use Biden (he is the current president).