Determining the optimal cut-off scores for the Workplace Bullying Inventory
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Determining the optimal cut-off scores for the Workplace Bullying Inventory

Marie Hutchinson Associate professor, Health and Human Sciences, Southern Cross University, Lismore, New South Wales, Australia
Joanne Bradbury Lecturer, Southern Cross University, Gold Coast, Queensland, Australia
Graeme Browne Senior lecturer, University of Newcastle, Callaghan, New South Wales, Australia
John Hurley Associate professor, Southern Cross University, Coffs Harbour, New South Wales, Australia

Background Over the past two decades, there has been considerable research into workplace bullying. One area that remains poorly developed is a tool with the capacity to accurately differentiate between exposed and unexposed employees.

Aim To determine optimal cut-off scores for the Workplace Bullying Inventory (WBI) that accurately classify cases of exposure to workplace bullying.

Discussion Secondary analysis of data collected from Australian public sector employees (n=2,197) was conducted. Receiver operator characteristic (ROC) curve analysis was used with a minimum sensitivity of 80%, to determine those scores on the WBI that corresponded with the highest accuracy of the tool to distinguish cases from non-cases. The results suggest using a cut score of 29 from the total score on the WBI (possible range: 18-90). When compared to a sum-score from a single dichotomous self-report variable, the cut-off score estimated a more conservative bullying rate. The single-item rate was potentially inflated by misconceptions about what constitutes bullying in the workplace.

Conclusion Employing validated cut-off points for exposure provides an objective threshold for establishing exposure to workplace bullying. The results of the analysis provide a more rigorous approach to quantifying exposure to workplace bullying, in a tool that has been designed and tested in the nursing workforce. This is the first such tool with empirically-derived, discriminant accuracy.

Implications for practice It is common for nurse researchers to employ sum-scores from single items to identify exposure to workplace bullying. By providing reliable cut-off points for exposure, this study offers standardised, diagnostic accuracy for researchers, clinicians and managers.

Nurse Researcher. 25, 3, 46-50. doi: 10.7748/nr.2017.e1543


Peer review

This article has been subject to double-blind review and has been checked for plagiarism using automated software

Conflict of interest

None declared

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Received: 11 December 2016

Accepted: 05 April 2017

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