A caveat on using single‐item versus multiple‐item scales

Single‐item measures are quick and easy to use; however, methodologists advocate the use of multiple‐item measures. Recently, this stringent viewpoint has been challenged. Using the classical formula for the correction for attenuation and job satisfaction data, they demonstrated that meaningful reliability estimates can be calculated for single‐item measures. This study examined this approach using “belief in a just world” data from two instruments. The findings provide qualified support for single‐item measures when the underlying constructs are homogeneous, but these findings are not strong enough to challenge the view that multiple‐item measures are needed to measure relatively complex constructs reliably. Practitioners and researchers should be wary of single‐item measures.