7 lessons Intro stats (STAT 101) and AP Statistics students
Intro to Statistics
7 concept-first lessons with worked examples you can follow on paper or in a spreadsheet. The goal is understanding what the numbers mean, not memorizing formulas.
All lessons
- 🎲 1. Data, variables and samplingCategorical vs. quantitative, populations, samples and bias
- 🎯 2. Mean, median and modeMeasures of center, and which one to use when data are skewed
- ↔️ 3. Spread: range, IQR and standard deviationHow spread out the data are, and how to read a box plot
- 🔔 4. The normal curve and z-scoresThe 68–95–99.7 rule and comparing values on different scales
- 📉 5. Correlation and regressionScatterplots, r, the line of best fit — and causation
- 🎯 6. Confidence intervalsEstimate ± margin of error, and what “95% confident” means
- ⚗️ 7. Hypothesis tests and p-valuesNull and alternative, the p-value, significance and errors
✏️ Practice: Scientific calculator with a statistics tab (mean, median, standard deviation)
About this course
The course covers the first half of a typical college intro statistics course or AP Statistics: describing data, the normal model, relationships between variables, and the logic of inference. Each lesson has a worked example with small, real-looking numbers.
You can do every calculation with the site’s scientific calculator (Statistics tab) or the online spreadsheet, using functions like AVERAGE and STDEV in Excel or Google Sheets.
Questions & answers
- Do I need strong math skills for intro statistics?
- Basic algebra is enough. Intro stats is more about reasoning — choosing the right summary, interpreting results and spotting misleading claims — than heavy calculation.
- Sample or population standard deviation?
- When your data are a sample used to learn about a larger population (almost always in research), use the sample standard deviation, which divides by n − 1. In Excel: STDEV.S.
- What does a p-value really mean?
- If the null hypothesis were true, the p-value is the probability of getting results at least as extreme as yours. It is not the probability that the null hypothesis is true. Lesson 7 explains it.
- Is the course free?
- Yes, with no sign-up.