Footnotes

• Correction notice This article has been correcetd since it first published online. The sentence starting ‘We tested two additional response options’ has been corrected.

• Contributors Conceptualisation: GB, JAH, JS. Design of data collection: GB, EMN, ZBG, JS, JAH. Data collection: EMN, JAH. Analysis: GB, EN. Writing and review of the manuscript: GB, EMN, ZBG, JS, JAH. Approval of the final manuscript: GB, EMN, ZBG, JS, JAH.

• Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

• Competing interests No, there are no competing interests for any author.

• Patient consent for publication Not required.

• Provenance and peer review Not commissioned; internally peer reviewed.