Assessment of parameters to interpret the need for recovery in ergonomics: the need for recovery scale

Abstract

Introduction: The Need for Recovery Scale (NFR) has been widely used in Ergonomics. However, there is no
cut-off value validated in the literature which allows identifying in consensual way high levels of need for recovery.
Objective: Compare the use of different mathematical parameters to interpret data from NFR, i.e. tertile, quartile, and mean value, as well as cut-off values already suggested in the literature, in order to investigate the behavior of these parameters in the identification of high levels of need for recovery. Materials and methods: This study had the participation of 679 workers, out of which 192 were industrial laborers, 128 were nursing professionals, and 359 were call-center operators. Data collection was conducted by means of questionnaires. Results: Data distribution significantly varied between groups. The cut-off values defined according to data distribution (tertile and quartile) were similar to some cut-off values described in the literature. The various cut-off values proposed did not identify similar amounts of workers with high levels of need for recovery. The non-normal distribution of two out of these populations showed that the mean value may not be an adequate parameter. Discussion and conclusions: The different mathematical parameters used to identify high levels of need for recovery did not lead to equivalent results, suggesting caution to be selected. While studies with  larger populations are not available, the use of data distribution within a group itself is more recommended than the use of fixed points to identify high levels of need for recovery.