Fig. 1

A Six interrupted time series (ITS) studies examining the effect of supermarket policies on purchases of common checkout foods [11]. The crosses represent data points, the solid lines represent the pre- and post-interruption trend lines and the dashed line represents the counterfactual trend line. The vertical dashed green line indicates the time of the interruption. B Forest plots depicting study-level and meta-analysis estimates of immediate level-change (left) and slope-change (right). ITS interrupted time series