Footnotes

• Handling editor Vikram Deshpande.

• Contributors PJT had the initial concept which was expanded by/contributed to all three coauthors; first draft written by JLVR with DH and PJT amending; all three authors approved the final submission. PJT is the guarantor.

• 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 PJT is an associate editor of the JCP.

• Provenance and peer review Commissioned; internally peer reviewed.