Statistics

Read distributions, question samples, and explore how groups and outliers change a conclusion.

9 lessons

Read labels and units, then combine two series to find totals, differences, shares and percentage changes.

6 min

Compare the mean and median, then explain what an unusually large value changes.

4 min

See why equal means can hide different variability and what standard deviation summarizes.

4 min

Distinguish chance differences between random samples from systematic selection bias.

4 min

Goes with Sampling

Combine totals correctly and see how changing group proportions can reverse a comparison.

6 min

Investigate influential observations while keeping correlation separate from causation.

4 min

Use random assignments to understand how surprising a difference is.

5 min

Understand what confidence intervals cover, what more data changes and what bias leaves behind.

6 min

Distinguish a real effect from the change expected after selecting unusual first results.

6 min

Ready to try?

Take a method into a practice, or discover something new.