Sample size

[Sunil K Upneja]

What should be the adequate size of sample for an experimental study? Pls reply.

[Rakesh Mohindra]

The larger your sample size, the more sure you can be that their answers truly reflect the population. This indicates that for a given confidence level, the larger your sample size, the smaller your confidence interval. However, the relationship is not linear (i.e., doubling the sample size does not halve the confidence interval).

there many other parmeters which need to be consider for determining the sample sizes for various measure of variables. To calculate sample sizes, there are many online sample sizes calculator on the  web. 

you can try at http://hedwig.mgh.harvard.edu/sample_size/js/js_associative_quant.html for calculating your study sample size.

Generally to determine the power of study we need to give consideration for suitable samle size in most of the health sc studies.

[Rakesh Mohindra]

look for more details   at    http://extension.psu.edu/evaluation/pdf/TS60.pdf