Sample Size
01 Definition
Sample Size meaning: The number of users or sessions included in a test or analysis.
Sample size is how many visitors, sessions, or conversions a test collects. Larger samples produce more reliable results and can detect smaller differences. Too small a sample raises the risk of a misleading outcome. Analysts often calculate the needed sample size in advance from the effect they hope to detect.
Why it matters
How Sample Size fits the work
Planning sample size before a test keeps you from stopping too early on noisy data or running far longer than the decision requires.
In context
The calculator said we needed a sample size of 8,000 visitors per variant to detect a 3 percent lift with confidence.
Practical note
Calculate the required sample size before launch using your baseline rate and the smallest lift worth detecting. Ending a test the moment it looks significant inflates false positives.