Abstract

Evidence-based Management (EBMgt) and Evidence-Based Management + (EBMgt +) are two approaches to management according to which managerial decisions should be based on the best available evidence, as this increases the likelihood of their effectiveness. In these approaches, four types of evidence are considered: evidence from the scientific literature, from practitioners, from the organisation and from stakeholders. In EBMgt +, evidence is characterised as a three-place relation between information, a claim and a method. In many circumstances, probability sampling methods (PSMs) are the best methods to gather the abovementioned types of evidence. We present a case study concerning harassment in the workplace to illustrate a circumstance in which fact-finding methods, rather than PSMs, are the best methods to gather evidence. We argue that information thus gathered should count as evidence in the spirit of EBMgt +. However, while part of the evidence needed in the case study comes from the stakeholders, it does not fit the characterisations of ‘evidence from stakeholders’ considered in EBMgt and EBMgt +. Therefore, we disentangle sources and types of evidence which, in turn, enables us to characterise a new type of evidence – testimonial evidence – that should be included in the theory of evidence-based management. Differentiating between sources and types has the potential to bring theory and practice closer together, whereas including testimonial evidence has the potential to make the theory of evidence-based management applicable in a wider range of circumstances, such as trade secret theft and conflicts of interest.