I need to calculate minmal sample size of user for definition design in case response is a scale data and is given by each user (like survey data). Which calculator do I need to use?
There are caclulator for conversion rates here http://www.evanmiller.org/ab-testing/sample-size.html
But scale data I think needs a diferent type of calculator.
I am working on multivariate testing (DoE) of a prototype. I want to use UX(usability) metrics as outputs in user testing.
Metrics are scale ratings (1 to 10) that each user provides plus some output is continuous data such as time on task.
It is 2 level Definitive design. I want to see minimal effect of 20% and I can guess variance only from similar studies.
I can use G-power, SAS JMP or some online calculator.