Rhetorical ploys in evidence presentations

Here is the beginning of a collection of rhetorical ploys in evidence presentations, verbal moves that replace real evidence.

FAUX CONSERVATISM This takes the form of “Our results are conservative; we made conservative assumptions about the model.” The claim is that possible biases in assumptions work against the view advanced by the researcher. This is in fact an implicit error statement. Such claims are sometimes a rhetorical tactic that substitutes verbal fudge factors for quantitative assessments of error. See for example the Boeing/Columbia slide with the headline: Review of test data indicates conservatism for tile penetration

IGNORING SELF-CONTRADICTION See the Boeing slide. See also Richard Feynman’s example in his Challenger report at page 137 of “What do you care what other people think?”:

SIGNIFICANCE This is a pun on “statistical significance.” Substantive significance is claimed as a result of statistical significance tests.

BIZARRE LEVELS OF STATISTICAL SIGNIFICANCE The null hypothesis is rejected at the .000000001 level and that extremeness is claimed as evidence for the researcher’s alternative hypothesis. The “significance” level is largely a function of the ridiculousness of the null hypothesis, the (sometimes contrived) sample size, and the data results. In these calculations, the assumption of the independence of observations is often ignored, thereby inflating the probability level.

EDITORIAL ADVERBS PLACED IN FRONT OF NUMBERS Characterizing the data in advance of saying what the data are. Note the 2 uses of the word “only” in this news report: “Despite the costs, there is a limit to what the public will accept, according to the poll presented to the Harvard forum. Only 41 percent supported a special tax on junk food – an idea Sturm said would be difficult to administer – and only 37 percent said they strongly supported requiring restaurants to list calorie content on their menus.” (Extra Pounds Cost Big Dollars: Rise In U.S. Obesity Labeled A Crisis, August 16, 2003, by John A. MacDonald) Note also the “only 37 percent said they strongly supported”; how many supported, strongly or not so strongly? How many strongly opposed?