# how to determine sample size for continuous metric

many online sample size calculator like http://www.evanmiller.org/ab-testing/sample-size.html only have sample size calculation for discrete metric(like conversion rate)
how to calculate sample size for continuous metrics like sales-per-user, gmv-per-user, sum-of-gmv, gmv-increase-ratio • To properly compute a sample size, you need to see the underlying statistical problem. Often the purpose is to know how much data you need to achieve some precision. To define a precision you need a underlying statistical model. Since i don't know anything about marketing, i don't know which underlying statistical model is used. if you know i can provide a sample size. – PauZen Sep 13 '19 at 9:40
• Perhaps hedwig.mgh.harvard.edu/sample_size may provide some help. And a book reference: Shein-Chung Chow (Ed.). Sample Size Calculations in Clinical Research. Chapman & Hall / CRC Biostatistic Series. Both are more focused on clinical studies. – Ertxiem - reinstate Monica Sep 13 '19 at 12:48
• In what sense is conversion rate a "discrete metric"? In this context that value would naturally be a parameter of a statistical model: that is, it's an idealized number, not a statistic. It could have any value between 0 and 1. – whuber Sep 13 '19 at 14:03