How to Lie with Statistics Fallacies and Their Consequences

What is a “Fallacy”? Fallacy In general, a mistaken belief based on a misleading, faulty, or unsound argument. In logic, a failure in reasoning that renders an argument invalid.

Some Common Fallacies Circular Reasoning/Begging the Question: Any argument that includes the conclusion among its premises (assuming what you meant to prove)—”Chocolate is healthful because it is good for you.” Probability Fallacy: Assuming something will happen because it is probable that it will happen. (Example: Dave: Did you know that Jesus was gay?//Tim: And why do you say that?//Dave: You have to admit, it is possible!//Tim: So is the fact that you are a moron.) Straw Man: an argument based on misrepresentation of an opponent's position. (Example: “After Will said that we should put more money into health and education, Warren responded by saying that he was surprised that Will hates our country so much that he wants to leave it defenceless by cutting military spending.”

Slippery Slope: Assuming that a small first step will lead to a chain of events leading to an unwanted outcome. Based on probability fallacy. (Example: “If you allow the students to redo this test, they are going to want to redo every assignment for the rest of the year.”) Ad hominem: Attacking the person presenting the argument rather than the argument they present. (Example: “You cannot trust anything that man says.”) Post hoc ergo propter hoc (literally: “After which, therefore because of which”, aka Causation/Correlation Fallacy): Assuming that if A is highly correlated with B, then A causes B.

Huff on Smoking and Bad Grades High correlation between smoking and bad grades in college. Conclusion: Smoking causes bad grades. Huff: this is no more plausible than the claim that bad grades cause smoking. Equally plausible alternatives: Third factor alternative: being sociable leads to smoking and to bad grades (too much partying, not enough studying) Correlation is strictly chance Dual causation: e.g., high income results in investing in stocks, which results in high income.

Positive Correlation Turning to a Negative Correlation: e. g Positive Correlation Turning to a Negative Correlation: e.g., more rain causes higher corn yield….to a point. Other fallacies relevant to sociology: Gambler’s fallacy (JP explains) Small sample size (discuss) Biased sample (discuss) Cherry picking (discuss) Priming/Poisoning the well (discuss)