Statistics Cheat Sheet 2026

The 30 highest-yield Statistics facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. In reliability engineering within quality assurance, the 'bathtub curve' describes the failure rate of a product over time. The three regions of this curve are: → Burn-in, random failure, and wear-out
2. What is a risk mitigation strategy in Statistics practice? → Implementing controls that reduce the likelihood or impact of identified risks
3. The concept of 'data governance' in regulatory compliance primarily refers to: → Policies ensuring data quality, integrity, and authorized use
4. In environmental regulation, which statistical approach does the EPA use to set National Ambient Air Quality Standards? → Risk-based standards using specified percentile exposures
5. Which sampling method assigns each member of the population a unique number and selects individuals using a random number generator? → Simple random sampling
6. A statistician needs to explain Type I and Type II errors to a clinical trial sponsor. Which real-world framing is most effective? → Type I: approving an ineffective drug; Type II: rejecting an effective drug
7. Which SQL aggregate function computes the arithmetic mean of a numeric column named 'score'? → AVG(score)
8. A researcher uses convenience sampling by surveying students in one university class. Which threat to validity is MOST relevant? → External validity — limited generalizability
9. Which probability distribution is appropriate for modeling the number of successes in a fixed number of independent trials? → Binomial distribution
10. A marketing team asks if an A/B test result is 'good enough to act on.' What statistical concept should guide your answer? → The combination of statistical significance, effect size, and practical business impact
11. A client insists that a correlation of 0.3 between advertising spend and sales 'proves' advertising causes sales. What is the statistician's best response? → Explain that correlation does not imply causation and suggest an experimental design
12. Which control chart should be used when the subgroup size n = 1 (individual measurements)? → Individuals (I) and Moving Range (MR) chart
13. Which U.S. law established the requirement for companies to maintain internal controls over financial reporting and have them audited? → Sarbanes-Oxley Act
14. A statistician is presenting regression results to a non-technical board. Which approach best communicates a significant predictor? → State 'for every 1-unit increase in X, Y increases by B units on average'
15. In multiple regression, what does multicollinearity refer to? → High correlation among predictor variables
16. In Microsoft Excel's Data Analysis ToolPak, which tool generates a table showing regression coefficients, R-squared, and ANOVA output? → Regression
17. What is the variance of the dataset {2, 4, 4, 4, 5, 5, 7, 9}? → 4
18. A researcher tests whether a coin is fair by flipping it 100 times and getting 60 heads. He sets α=0.05 and calculates p=0.057. What conclusion does he draw? → Fail to reject H₀; there is insufficient evidence to conclude the coin is unfair
19. When reporting statistical results in an executive summary, which element should always be included alongside a p-value? → An effect size measure
20. A loss severity distribution is modeled with a lognormal model. If the underlying normal variable has μ = 10 and σ = 1, the median loss is: → e¹⁰ ≈ $22,026
21. In evidence-based practice, the PICO framework helps researchers formulate: → A well-built clinical question
22. In SAS, the PROC FREQ procedure is primarily used for: → Generating frequency tables and chi-square tests for categorical data
23. What is a one-tailed hypothesis test used for? → Testing for an effect in a specific direction
24. What is the effect of increasing the significance level (α) from 0.05 to 0.10 on a hypothesis test? → Increases the probability of a Type I error and raises power
25. In Design of Experiments (DOE) applied to quality improvement, a '2^k factorial design' refers to an experiment with: → k factors each tested at exactly two levels
26. The empirical rule states that approximately what percentage of data falls within 2 standard deviations of the mean in a normal distribution? → 95%
27. In R's ggplot2 package, which function adds a linear regression line to a scatter plot? → geom_smooth(method='lm')
28. A neuroscientist measures reaction times before and after caffeine intake for 15 subjects. Which test is most appropriate? → Paired t-test
29. A statistician uses Python's statsmodels library to fit an OLS regression and inspects the Durbin-Watson statistic. What assumption does this statistic test? → Independence of residuals (autocorrelation)
30. In the context of regression, what is overfitting? → A model that fits the training data too closely and performs poorly on new data