Statisticsdrill

All 53 statistics problems

Statisticsdrill is applied statistics practice in your browser. Every problem is a template that generates a fresh sample or scenario on each attempt: ticket times, survey shares, conversion rates, sales data. Enter one number, see the worked steps and the spreadsheet function that does it for you. The problems are listed here level by level. 5 are free without an account; Pro unlocks the rest.

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Level 1: Describing data

Mean, median, mode and range, sample vs population standard deviation, z-scores, percentiles with a stated method, the coefficient of variation and weighted means.

  1. Mean of a sampleFree
  2. Median of a sampleFree
  3. Mode of a data setFree
  4. Range of a data setFree
  5. Sample standard deviationFree
  6. Population standard deviationPro
  7. z-score of one valuePro
  8. Percentile (inclusive method)Pro
  9. Coefficient of variationPro
  10. Weighted meanPro

Level 2: Probability

Complements, the addition and multiplication rules, conditional probability from a two-way table, Bayes with a screening test, total probability, expected value and counting.

  1. At least one, by the complementPro
  2. Addition rule: A or BPro
  3. Multiplication rule: all succeedPro
  4. Conditional probability from a tablePro
  5. Bayes: a positive screening resultPro
  6. Total probability across groupsPro
  7. Expected value of a raffle ticketPro
  8. Permutations: ordered choicesPro
  9. Combinations: unordered choicesPro
  10. Sampling without replacementPro

Level 3: Distributions

Binomial exactly k and at least k, Poisson, normal areas and percentile cutoffs, the sampling distribution of the mean and the normal approximation.

  1. Binomial: exactly kPro
  2. Binomial: at least kPro
  3. Binomial standard deviationPro
  4. Poisson: exactly kPro
  5. Poisson: at most kPro
  6. Normal: between two valuesPro
  7. Normal: above a valuePro
  8. Normal: percentile cutoffPro
  9. Sampling distribution of the meanPro
  10. Normal approximation to the binomialPro

Level 4: Inference

t and z intervals, required sample size, one-sample and paired t tests, two-proportion z tests and chi-square tests of independence, with a reject or fail to reject decision.

  1. Critical t value for an intervalPro
  2. Margin of error for a mean (t)Pro
  3. Confidence interval for a proportionPro
  4. Sample size for a meanPro
  5. Sample size for a proportionPro
  6. One-sample t statisticPro
  7. Two-sided t test: p-value and decisionPro
  8. One-sided t test: p-value and decisionPro
  9. Two-proportion z testPro
  10. Paired t testPro
  11. Chi-square test of independence (2 x 3)Pro
  12. Chi-square 2 x 2: p-value and decisionPro

Level 5: Relationships

Correlation, covariance, regression slope and intercept, predictions and residuals, R squared, reading a slope in units, and A/B test lift and significance.

  1. Correlation coefficientPro
  2. Regression slopePro
  3. Regression interceptPro
  4. Predicted value from a fitted linePro
  5. Residual of one observationPro
  6. R squaredPro
  7. Interpreting a slope in unitsPro
  8. A/B test: relative liftPro
  9. A/B test: p-value and decisionPro
  10. Testing a correlationPro
  11. Sample covariancePro

Try the first five problem types free.

No sign-up needed for the first five, with unlimited fresh numbers. If it works for you, Pro unlocks all 53, and a free account saves your progress across devices.

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