What is sample size? Sample size measures the number of individual samples measured or observations used in a survey or experiment. For example, if you test 100 tyres for wear and tear, your sample size is 100. If an online survey returned 93,000 completed questionnaires, your sample size is 93,000.
What is a sample size calculator? A sample size calculator provides a visible method of computing the number of visitors required for a test to be statistically significant (e.g. the needed amount of visitors you need to assess that a lift/loss of x% can be trusted with 95% confidence).