Sara Said:

Confused! What should my sample size be for a cross-sectional study?

We Answered:

The best I can suggest, based on what you've presented is that you should use a chi-square test for independence (a.k.a. contingency table). You would create a matrix of integer counts. For example, the 3 columns would be the 3 ethnicities. The rows could be 3 (or more) classifications of quality of life. The data in the matrix would be the total counts in the appropriate cells. The sample size should be large enough to assure at least 5 expected values in each cell.
The method of analysis is beyond the scope of this answer, but is simple and can be found in any statistic book, or present the data here for me, or someone, to answer.

Debbie Said:

How to calculate sample size for cross-sectional study in epidemiology?

We Answered:

Do an internet search on "statistical power". That will tell you what you need to do. To get free software to calculate it, search on GPower.

Paula Said:

questions asked in cross sectional study on prevalence of diarrhoea in children under 5 yrs?

We Answered:

You have used 2 words with totally different meanings. Prevalence refers to the total number of cases of a disease in a given population at a specific time. The average infant has an attack of infective diarrhoea about once every 9 months in the UK.

Relevance would require explanation before the question could be answered.

Jim Said:

Can u releive my confusion about longitudinal or cross sectional study?

We Answered:

You are tracing changes - or lack of changes - in the protozoa populations of the water you are sampling over the course of a year. I believe that is a longitudinal study of the water.

Roland Said:

Can someone please explain the disadvantage of a cross sectional study?

We Answered:

look carefully: studies+disadvantages&meta=&aq=f&oq=" rel="nofollow">http://www.google.co.uk/search?hl=en&q=c…