Many individuals, not least in the media, use ambiguous, inexplicit “Weasel Words” such as: may, might, could, can, scientists have shown that… They all have the same effect of presenting as true things that are not necessarily valid.
For example newspapers, particularly popular tabloids, often run articles along the lines of:
Studies at ABC University have shown that drinking even 2 glasses of wine a day may endanger your health. Scientists at the University have shown that drinking over 2 glasses of wine can increase your chance of XYZ disease by 20%.
This made up story is typical of the sort of article that seems to be the staple in many tabloid newspapers. The very strong claim is in the headline “Alcohol Kills”, then the body of the article presents the evidence.
The things to look out for here when you determine your own level of acceptance for these types of stories or word of mouth rumours are:
- Always the Weasel Words such as may, can, could…. express a possibility, not certainty. However the story presents the claim (in this case Alcohol Kills) as a fact. Use of such Weasel Words is perfectly reasonable when indicating that there is some doubt or that there is little evidence to support a statement, but in this case the words are being used in the context of a much more strongly presented argument.
- Unspecified source attribution, as in “Scientists” are a sure sign of potential exaggeration.
- No indication of the evidence (or how it was collected) that supports this claim also is common in these sensationalist articles and rumours.
- Risks expressed in relative terms are also always suspect. Claims like the “a 20% increase in your chance of some disease.” If the base case is 0.01% chance of the disease then an increase to 0.012% is not really a cause for concern.
This does not mean the claims are wrong it just means that the grounds for believing the implied story are less than robust.
Invariably these stories are based (if they are based on any evidence at all) on statistical analysis of a sample of the general population. So reputable sources should quote the statistical information that supports the claim such as sample size, whether it is a random sample or not, confidence levels and probability. With this additional evidence you can more readily determine the validity you will place on the stated claims.
The presence of the Weasel Words is a good indicator that care needs to be taken in evaluating the validity of any claims. If the claims are only supported by Weasel Word evidence, then treat with suspicion the accuracy of this evidence and look for more certain sources of evidence.