JAMA rules of engagement on causal and predictive language

Erik, Witold, and I recently published a paper in the Journal of the American Medical Association. This was cool. A day after the paper came out, I ran into someone I know on the street and he said he liked our article. That’s kind of amazing, as usually it seems that nobody reads anything. We’ll have to publish in JAMA more often.

As part of the publication process, we were sent some general reporting requirements per JAMA standards. Here’s the part that will interest you:

USE OF CAUSAL LANGUAGE
Use of causal language (including use of terms such as “effect,” “efficacy,” “cause,” and “x increased y”) should be used only for randomized trials. For all other study designs (including meta-analyses of randomized trials), methods and results should be described in terms of association or correlation (eg, “x associated with an increase in y”) and should avoid cause-and-effect wording. Avoid use of the words “predict” and “predictive of” for reports of observational studies assessing independent and dependent variables, unless your study design is a diagnostic/prognostic study and has used an appropriate approach to quantifying predictive performance such as (but not limited to) split sampling, cross-validation, or bootstrapping.

On the first item . . . Wow. I wonder if they’d let you write, “Cigarette smoking causes cancer in humans”?

I guess the second item is ok if it’s interpreted broadly enough. For example, Bayesian methods use an appropriate approach to quantifying predictive performance, so I guess that would be included in the “not limited to” category.