Rebuttal: When it comes to scientific inference, sometimes a cigar is just a cigar

We are grateful to the editors for suggesting that our submission become a debate piece, as we value critical discussion. We are gratified that the three invited counterpoints not only agree with our position but add useful insights. Elwood summed up our view when (referring to the White Paper on the U.S. National Children’s Study1) he commented that ‘the concept of external validity given confuses statistical inference with scientific inference’.2 Richiardi et al. echoed our point that representativeness is not desirable even if the goal is to study effect-measure modification: ‘Similarly using non-representative samples may enhance our ability to assess heterogeneity with regards to potential effect modifiers, e.g. by ensuring that there are adequate numbers in each of the ethnic groups to be considered if we suspect or are interested in potential modification by ethnicity’.3 And we especially liked Nohr and Olsen’s quotable remark that ‘Representativeness is time and place specific and will therefore always be a historical concept … .’4