Understanding convictions, your own included

Noting that a vote is more frequent where a certain group lives does not mean that this group votes that way. This very common slide has had a name for more than seventy years.

Answering yes or no is quicker, and it is also what manufactures the most artificial opinions. Here is what is gained by asking how much, rather than which side.

Adding dimensions to a political description makes it both more faithful and more fragile. Here is the trade-off, stated without marketing.

Sorting people into named profiles makes a result legible. It also creates an illusion: that of clear frontiers where there are only degrees.

Answering forty questions requires attention, and attention falls. Wording half the items the other way round is one of the few protections that work.

A rarity percentage impresses, but it means nothing until one has specified rare compared with what, and measured how.

Finding oneself in the middle of a scale does not have a single meaning. Three very different situations produce the same point, and it is worth knowing which is yours.

A well-built test measures something real. It does not measure what is often attributed to it, and it is more useful to say so than to let people believe otherwise.

A question can produce the answer it expects without anyone having cheated. Here are the defects that suffice to create an opinion out of nothing.

Situating yourself in relation to someone whose positions you know makes a result speak. The exercise is useful on three conditions, and misleading if they are forgotten.

Finding a different result a few years later is not a sign that one of the two measurements was wrong. Three distinct causes can explain it.