While planning clinical study like RCT on diseases like COVID-19, how can we calculate the sample size when exact disease prevalence is not available
When this information is not available in the literature or a pilot-study cannot be carried out, the value that maximizes sample size is used (50% for a fixed value of sample error).
Dear Amit
If the population is known (sample size calculation with finite population) then you can use any of the following calculators to know the sample size
1. https://www.surveysystem.com/sscalc.htm
2. https://apps.who.int/iris/handle/10665/40062
3. https://www.calculator.net/sample-size-calculator.html
4. Article Sample Size Determination in Health Studies: A Practical Manual.
5. Article Sample size calculation
But as I understand it is not the case. You have not any idea about the population ( here in your question i.e. the prevalence of any disease) so you need to use the sample size calculation with a non-finite population.
And in this case,(sample size calculation with non-finite population) you go with the Cochran formula, for this please follow the link:
https://www.statisticshowto.com/probability-and-statistics/find-sample-size/
or you can visit any other link related to Cochran formula (Sorry I do not know how to type the formula here, so please go to any of the link or just search)
1. https://www.researchgate.net/post/Is_that_possible_to_use_Cochran_formula_sample_size_determination_for_heterogeneous_groups_populations
2. https://gist.github.com/marcoscaceres/7137166
There are some pages related to "determine the sample size from an unknown population" is on researchgate with the following links:
1. https://www.researchgate.net/post/How_can_we_determine_the_sample_size_from_an_unknown_population
2. https://www.researchgate.net/post/How_do_I_determine_sample_size_for_each_strata_in_survey2
Please find some of the files (related to sample size calculation when the population is not known) as attachments.
Hope you find all the information useful in the way to determine sample size as the case you have.
Happy researching...
Hi, either way you will find some useful tools at:
http://powerandsamplesize.com/Calculators/
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