The Brief IPQ does not have 'robust psychometrics': Why there is a need for further developmental work on the Brief...

In this reply to Broadbent, Kaptein, and Petrie's commentary, we agree that our 'think aloud' study has limitations. However, we consider that the commentary goes too far in claiming these invalidate our findings. The authors of this commentary cite as a major limitation our use of a Dutch translation of the Brief IPQ. However, their reservations about this translation were not sufficient to prevent them from attempting to publish a paper describing the extended process behind its translation and validation. In contrast to the claims made, we consider that the Brief IPQ has poor concurrent validity, content validity is neglected, and no evidence is provided regarding discriminant validity. Our conclusions are described as 'overstated'-but we consider that calling into question the content validity of the Brief IPQ is fairly temperate, given the lack of attention it has received. Further, we cannot see how anyone could reasonably disagree with 'further developmental work with this questionnaire may be needed to better quantify and resolve the problems identified'-to do so it is to claim that the Brief IPQ is perfect! In sum, we think a more constructive response from the authors of this critique would be to engage with our observations, to improve the Brief IPQ.