Glossary · Phase 2 · Math, when you need it
Resample
Draw a new sample from your data, picking rows at random with replacement, to mimic collecting fresh data.
Picture your 300 receipts in a hat. Draw one, write down its amount, and put it back. Repeat 300 times. Putting it back is called sampling with replacement. Some receipts get drawn twice, some not at all. The result is a new, slightly different pile of 300 receipts: a resample.
Try it now
Each run is 1,000 experiments. Each one measures the conversion rate from n visitors. Raise the visitors per experiment and watch the spread of measured rates shrink.
Learn it properly
Samples and confidence · Estimate from a sample and say how sure you are. About 30 minutes.
Other terms from the same lesson
- bootstrap: Estimating uncertainty by resampling your own data, with replacement, many times and seeing how much the answer moves.
- confidence interval: A range that probably contains the true value, given the data you sampled.
- margin of error: The plus-or-minus around an estimate, such as 3.2% ± 0.8%. It is usually about two standard errors.
- standard error: How much an estimate from a sample would wobble if you took a fresh sample. Bigger samples give smaller standard errors.
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