In Epstein’s book, Critical Thinking, Chapter 13 discusses the way numbers can be misleading or wonderful (if correct) in presenting claims.
When used correctly or should I say, honestly, numbers are very powerful. You can see immediately that numbers speak volumes when placed in a spreadsheet or presentation or used in oral communication, such as a speech, to support a claim. Numbers can also be used to lie and deceive its audience. This can lead to many very bad outcomes. For example, there are some companies that lie about their income, expenditures and revenue to the shareholders so that the company can continue to APPEAR to be in the black. The one thing about numbers is that you can make them look good on paper, but if you’re not paying the bills, eventually your company will go under.
Several examples of what to look for are:
1) Apples and oranges: a numerical comparison where it does not make sense to compare the items;
2) Two times zero is still zero: a numerical comparison that makes something look impressive but the base of the comparison is not stated. (like clothes on sale for 30% off; off the price or the suggested retail price?)
3) Percentage of what?
4) Graphs: can mislead or conceal claims “by not taking the base of the comparison to be zero, or by using bars, or by spacing the numbers on the axes in certain ways.”
5) Averages: get the average or mean by adding the numbers then dividing by the number of items. Median: midway mark; the same number of items above as below. Mode: number most often obtained. The mean or the mode is more significant than the average.