2 published guides
Data Analysis
Practical workflows for exploring, cleaning, and interpreting real datasets, from the first look at the data through to a conclusion you can defend.
Visit the topic hubStatistics, made usable
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73 published guides 25 calculators 4 applied hubs
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Build a strong statistical foundation
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Foundations
Core notation, vocabulary, and concepts for learning statistics, covering populations versus samples, variable types, and summation notation.
Descriptive Statistics
Core summaries for describing datasets: mean, median, and mode for center; variance, standard deviation, and range for spread; and skewness for shape.
Probability & Distributions
Probability rules, from single events to conditional probability, plus the normal, binomial, and Poisson distributions that model random outcomes.
Regression & Correlation
How variables relate to each other: correlation coefficients, lines of best fit, and linear regression for measuring an association's strength.
Inferential Statistics
Hypothesis tests, confidence intervals, p-values, and the reasoning for drawing conclusions about a population from a limited sample.
Applied statistics
Use statistics where decisions get made
Explore practical topic hubs now; in-depth Applied guides will appear here as they are published.
Showing all 4 Applied Statistics topics.
1 published guides
Experiments & Causality
How to design A/B tests and experiments that answer the question you asked, and how to separate genuine cause from coincidence in observational data.
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Forecasting & Time Series
Building and validating forecasts from time-ordered data: trend, seasonality, backtesting, and recognising when a model has quietly stopped working.
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Machine Learning Statistics
The statistical thinking behind machine learning: validation, overfitting, class imbalance, and reading model metrics without fooling yourself.
Visit the topic hubPopular calculators
Run the numbers, then understand them
Each focused calculator is free to use and paired with enough context to make the result meaningful.
- Mean Calculator Calculate the mean (average) of any set of numbers, see the sum and count used, and get the result instantly with no sign-up required.
- Standard Deviation Calculator Calculate sample or population standard deviation for any data set and see how far values typically spread from the mean, step by step.
- Z-Score Calculator Calculate a z-score from a raw value, mean, and standard deviation to see how many standard deviations it falls from average.
- Confidence Interval Calculator Calculate a z-based confidence interval for a population mean, showing the margin of error and the lower and upper bounds.
- Linear Regression Calculator Fit a least-squares regression line for paired x and y values, returning the slope, intercept, and correlation coefficient.
- Sample Size Calculator Estimate the sample size needed to estimate a population proportion at a chosen confidence level and margin of error.
- Frequency Distribution Table Generator Build a sorted frequency table from raw data, showing relative and cumulative frequency for each distinct value automatically.
- Probability Calculator Calculate simple probability from the number of favorable and total outcomes, and see the complement probability at the same time.