Anecdotes are an unreliable source for assessing the effects of an intervention
Claims about the effect of a particular intervention are often supported by anecdotes (stories) about how the intervention has changed certain organizational outcomes (e.g. performance, absenteeism).
However, the fact that an organizational outcome improved or declined after an intervention does not mean that the intervention caused the improvement or decline, or that other individuals, groups or organisations receiving the same intervention will also improve or decline. After all, the change might have occurred even without the intervention.
Anecdotes are stories that rely heavily on personal testimony and can therefore not be regarded as trustworthy evidence.