Problem
Raw totals can create misleading comparisons.
Action
Adjust measurements to a common scale before comparing them.
Outcome
You make more accurate judgments.
Chapter: Linearity - Less Like Sweden
Problem
A trend that looks straight nearby may bend over larger ranges.
Action
Check whether the relationship changes shape before extending it.
Outcome
You avoid faulty predictions.
Chapter: Linearity - Straight Locally, Curved Globally
Problem
An average can hide important differences within a group.
Action
Look at how values are spread across the population.
Outcome
You understand the data more accurately.
Chapter: Linearity - Everyone Is Obese
Problem
Large numbers are difficult to understand on their own.
Action
Express quantities using a reference people can easily imagine.
Outcome
You judge scale more clearly.
Chapter: Linearity - How Much Is That in Dead Americans?
Problem
A quantity can appear important without context.
Action
Measure each part as a share of the total.
Outcome
You assess significance more accurately.
Chapter: Linearity - More Pie Than Plate
Problem
Random events can create convincing patterns.
Action
Ask how likely the pattern is to appear by chance.
Outcome
You avoid false discoveries.
Chapter: Inference - The Baltimore Stockbroker and the Bible Code
Problem
Random noise can look like a real effect.
Action
Check whether the result survives controls and repeated testing.
Outcome
You identify genuine evidence more reliably.
Chapter: Inference - Dead Fish Don’t Read Minds
Problem
Unusual conclusions can be supported by coincidence.
Action
Require evidence that clearly exceeds what randomness would produce.
Outcome
You reach more reliable conclusions.
Chapter: Inference - Reductio Ad Unlikely
Problem
Weak methods can produce convincing but false findings.
Action
Examine how the evidence was collected and tested.
Outcome
You distinguish reliable results from unreliable ones.
Chapter: Inference - The International Journal of Haruspicy
Problem
Ignoring prior knowledge or new information leads to poor estimates.
Action
Combine existing knowledge with the latest evidence.
Outcome
You make more accurate judgments under uncertainty.
Chapter: Inference - Are You There, God? It’s Me, Bayesian Inference
Problem
Rare rewards can distract attention from poor odds.
Action
Calculate the average outcome across all possible results.
Outcome
You make better decisions under uncertainty.
Chapter: Expectation - What to Expect When You’re Expecting to Win the Lottery
Problem
Trying to avoid every mistake can reduce overall performance.
Action
Choose the option with the best average result over time.
Outcome
You achieve better long-term outcomes.
Chapter: Expectation - Miss More Planes!
Problem
Opposing forces can make outcomes difficult to understand.
Action
Identify the point where the effects become equal.
Outcome
You understand the system more clearly.
Chapter: Expectation - Where the Train Tracks Meet
Problem
Exceptional performance often contains a large element of chance.
Action
Adjust future expectations to a more typical level.
Outcome
You make more realistic forecasts.
Chapter: Regression - The Triumph of Mediocrity
Problem
Individual observations can be distorted by random variation.
Action
Use the central pattern in the data to guide estimates.
Outcome
You make more dependable predictions.
Chapter: Regression - Galton’s Ellipse
Problem
Variables can move together without causing each other.
Action
Look for evidence that one factor directly changes the other.
Outcome
You avoid mistaken explanations.
Chapter: Regression - Does Lung Cancer Make You Smoke Cigarettes?
Problem
Vague concepts cannot be analyzed consistently.
Action
Specify clearly what is being studied and how it is identified.
Outcome
You build stronger conclusions.
Chapter: Regression - Part V: Existence
Problem
A single average can hide important disagreement.
Action
Examine how opinions vary across people and groups.
Outcome
You gain a more accurate picture of collective beliefs.
Chapter: Regression - There Is No Such Thing as Public Opinion
Problem
Complex outcomes can seem mysterious when only the results are observed.
Action
Investigate the simple processes that create the observed behavior.
Outcome
You understand complex systems more deeply.
Chapter: Regression - “Out of Nothing I Have Created a Strange New Universe”