Measuring Usability Homepage
Quantitative Usability, Statistics & Six Sigma by Jeff Sauro



May 22, 2008 | asked by Deepali Mahajan :

Question : How to determine the sample size for comparing mulltiple parameters like Height , weight, Blood pressure , Blood parameters like blood glucose, total cholesterol, etc in two different populations?

Answer :

For each of those parameters you are wishing to estimate, you need to first how they are measured (as a continuous measurement or discrete--such as presence or absence). It looks like they might be continuous measurements.   The next thing you need is an estimate of the standard deviation, which is a required piece of information to calculate sample size for continuous data. 

You then need to know how you will be comparing the populations (will you be using a t-test, an ANOVA or just confidence intervals?).

Once you have that data, you'll want to know what amount of difference you'd hope to detect (e.g. is a 20 point cholesterol difference too large or small to be meaningful) and then use common levels of Power, such as .70, .75 and .80 to find out how large your sample needs to be.


How helpful was this answer?
Avg. Rating: 0 ( 0 )
Question Tags

Tag Name # Vote
ANOVA1
Power1
Sample Size1
t-test1

New Tag:   



User Provided Answers & Comments :
No user comments or answers posted yet.


Comment or Update Answer:
Name
Email Address Not Published