CALCULATORSAMPLE SIZE CALCULATOR FOR PREVALENCE STUDIES* USING RANDOM (NOT CLUSTER) SAMPLINGLevel of Confidence =95%Expected P =0.50.05* Suggested precision (d) is 0.05.Population Size (N) =31Sample Size TablePrecision (d)Sample Size (n)Suggestion for FPC applicationAssumptionNo FPCWith FPC(Normality)0.010.00 0.01960531 n/N>0.05. FPC should be applied.OK0.020.00 0.02240231 n/N>0.05. FPC should be applied.OK0.030.00 0.03106831 n/N>0.05. FPC should be applied.OK0.040.00 0.0460130 n/N>0.05. FPC should be applied.OK0.05 0.0538529 n/N>0.05. FPC should be applied.OK0.06 0.0626728 n/N>0.05. FPC should be applied.OK0.07 0.0719727 n/N>0.05. FPC should be applied.OK0.08 0.0815126 n/N>0.05. FPC should be applied.OK0.09 0.0911925 n/N>0.05. FPC should be applied.OK0.10 0.109724 n/N>0.05. FPC should be applied.OK0.11 0.118023 n/N>0.05. FPC should be applied.OK0.12 0.126722 n/N>0.05. FPC should be applied.OK0.13 0.135721 n/N>0.05. FPC should be applied.OK0.14 0.145020 n/N>0.05. FPC should be applied.OK0.15 0.154319 n/N>0.05. FPC should be applied.OK0.000000Enter desired precision here.FPC = Finite Population Correction

Step 1: Enter the expected P in proportion of One. (For example, if the expected prevalence is 30%, then P=0.3).

Step 2: Enter the population size (N) (maybe an estimate) from which the sample will be taken. (If the population size is very large but not known exactly (i.e. infinite population), then LEAVE IT BLANK).

Step 3: Decide the sample size (n) from the Sample Size Table based on desired precision. The second column is the sample size without using finite population correction (FPC) and the third is using FPC. We should use FPC if n/N is >.05 (Daniel, 1999). Suggestion is given in the 4th column.

Calculated sample size should meet the normal approximation assumption (Daniel, 1999). The 5th column reports about this assumption.

If you desire to use more specific precision such as d=0.025, you can enter manually at the bottom of the 1st column of the sample size table.

Note: You may save the calculated worksheet, but use ("File" "Save As..") and give a new file name as you wish, so that the original calculator will be preserved. You can also print this page ("File" "Print..").

FORMULA

FORMULAE USED IN THIS CALCULATOR

Formula without Finite Population Correction:

Formula with Finite Population Correction:

Reference:Daniel WW (1999). Biostatistics: A Foundation for Analysis in the Health Sciences. 7th edn. New York: John Wiley & Sons.

REFERENCE

Sample Size Calculator for Prevalence Studies

Version 1.0.01, April 2006

Copyright 2006 by Lin Naing, Than Winn & Rusli B Nordin. Anyone may freely use this calculator to perform sample size calculation. It may not be sold for commercial gain. This calculator may not be reverse engineered or decompiled. All other rights reserved.

Suggested citation for this calculator:Naing L, Winn T and Rusli BN. Sample Size Calculator for Prevalence Studies, Version 1.0.01. Available at: http://www.kck.usm.my/ppsg/stats_resources.htm

The web page http://www.kck.usm.my/ppsg/stats_resources.htm contains up-to-date information about the program. You can check and download the latest version there.

Reference:Daniel WW (1999). Biostatistics: A Foundation for Analysis in the Health Sciences. 7th edn. New York: John Wiley & Sons.

Copyright 2006. All rights reserved.