Measurement difficulties limit where statistical analysis can work: when you can't measure the outcome you care about (standard of living, happiness), lack a large enough comparable historical dataset, or can't run a randomized experiment, statistical prediction cannot answer the question.

Semmelweis's discovery that doctors moving from the morgue to childbirth without washing hands killed thousands of women was resisted partly because of his arrogance and poor marketing of the findings, illustrating that statistics presented poorly fail to persuade even when correct.

Randomized trials are far less vulnerable to author bias than regressions because it is easier to 'cook the books' on regressions; the Moving to Opportunity experiment exemplifies this—its funders expected vouchers letting poor families move to middle-class neighborhoods to dramatically improve life outcomes, but preliminary results across ~40 life-chance measures over years show little improvement.

Before roughly 1990 physicians rarely looked up patient-specific information because it was too time-intensive and they couldn't read the statistics; the internet now gives every physician a massive library, and graded treatments let even statistically unskilled doctors calibrate how much discretion to exercise.

Statistical analysis of growing conditions (rainfall, temperature) via multivariate regression predicts Bordeaux wine quality more accurately than traditional expert tasters, because the wine is unpalatable and imprecise to judge in its immature early months.

The clash of competing studies, especially in contentious areas, drives progress toward eventual consensus by drawing attention and accumulating studies; emerging consensus suggests concealed-weapons laws and the death penalty (vs. life imprisonment) have little impact either way, while the immigration-wages question remains unresolved.

A good test for intellectual honesty is whether you can name a statistical study you believe but don't like; if you only believe results you like, you're a biased consumer of evidence.

Physicians still fail to wash hands enough between patients despite scrubbing before surgery, and routinized clean-hands projects that force handwashing at fixed checkpoints have been shown to save lives.

Randomized testing of store layouts (planograms) shows that placing higher-markup toothbrushes at chest-high prime viewing level increases purchases, demonstrating that controlled experiments reveal causal merchandising effects.

There is an 'iron law of resistance' whereby traditional experts (wine tasters, baseball scouts, physicians) resist yielding their status to statistical number-crunchers, not purely on the merits but due to ego and dislike of outsiders telling them what to do.

Capital One combines historical data mining (correlating customer attributes to predict products before an operator even answers, and computing counter-offers for rate negotiations) with massive randomized experiments on mailings to identify which promotions cause more new accounts.

Evidence-based medicine has produced a systematic grading of the quality of evidence behind treatments, which creates competition among researchers to fill gaps and lets physicians who lack statistical training still rely on evidence grades rather than pure intuition.

The law of large numbers ensures that randomly assigned groups are statistically identical not just on average but in their full distributions, so any difference in outcomes can be attributed to the one variable being manipulated—making randomized results transparent and not requiring trust in the statistician.

Ayres predicts the next EBM revolution will strip physicians of their 'front-end' discretion over diagnosis and test ordering, as digital medical records let data determine which classes of patients should receive which tests based on when medical benefit exceeds cost.

In any institution with many frontline employees, roughly half will be below average, so designing the institution around the top 10% is irrational; routinizing decisions and removing some discretion is therefore likely to improve outcomes.

Regression output can report not just a point prediction but its precision (e.g., a 95% confidence range), so when data quality is low or the outcome is inherently random, the statistics themselves disclose that the prediction is imprecise.

The central claim is relative, not absolute: statistical prediction is not invariably accurate or precise, but in case after case it does better than human prediction—and counterintuitively, the more subtle and complex the prediction (more than ten causal variables), the worse humans do relative to even crude statistics, because humans cannot bring themselves to put the right weights on the big variables.

In a 2002 study, a crude statistical algorithm using only structural factors (was the government a party, region of origin, whether the lower court was liberal/conservative) predicted Supreme Court justices' affirm/reverse votes better than 83 legal experts, because the experts—though many had clerked on the Court—couldn't bring themselves to weight known patterns heavily enough (e.g., that the Court tends to reverse the Ninth Circuit).

LoJack (a hidden radio chip enabling police to track stolen cars) reduces car theft rates across an area, not just for equipped vehicles, and—unlike concealed handguns—there is no plausible theoretical mechanism by which LoJack could increase crime, since it is never used as an offensive weapon.

Multiple alternative approaches increasingly show that women who would have preferred to abort but did not take less good care of those children later, visible not only in the children's criminality but in a variety of other factors—supporting the Donohue-Levitt abortion thesis though it remains disputed.