Sample Size Webulator - Sampling from a Larger Population
 
  

 


This Webulator is based on the following sample size formula for a comparison study.

The [Zalpha ] and [Zbeta] terms are provided in the following tables. The area under the normal curve for the [Zbeta] term is illustrated in the Figure 1.




Conversion table to create the Z beta term
(one tailed probability estimate=0.05);
beta = 0.10 (power = 90%) ;
[Zbeta] = 1.64		 (one tailed probability estimate=0.06);
beta = 0.12 (power = 88%) ;
[Zbeta] = 1.55
(one tailed probability estimate=0.07);
beta = 0.14 (power = 86%) ;
[Zbeta] = 1.48		 (one tailed probability estimate=0.08);
beta = 0.16 (power = 84%) ;
[Zbeta] = 1.41
(one tailed probability estimate=0.09);
beta = 0.18 (power = 82%) ;
[Zbeta] = 1.34		 (one tailed probability estimate=0.10);
beta = 0.20 (power = 80%) ;
[Zbeta] = 1.28

Conversion table for alpha and percent confidence to Z
(alpha probability estimate of 0.10)=90%
[Zalpha] = 1.64		 (alpha probability estimate of 0.09)=91%
[Zalpha] = 1.70
(alpha probability estimate of 0.08)=92%
[Zalpha] = 1.75		 (alpha probability estimate of 0.07)=93%
[Zalpha] = 1.81
(alpha probability estimate of 0.06)=94%
[Zalpha] = 1.88		 (alpha probability estimate of 0.05)=95%
[Zalpha] = 1.96
(alpha probability estimate of 0.04)=96%
[Zalpha] = 2.05		 (alpha probability estimate of 0.03)=97%
[Zalpha] = 2.17
(alpha probability estimate of 0.02)=98%
[Zalpha] = 2.33		 (alpha probability estimate of 0.01)=99%
[Zalpha] = 2.58

Only enter the numeric values without special characters for the expected mean, the expected standard deviation, the Zalpha,the Zbeta, and the percent difference between expected and actual, in the appropriate Webulator cells and then click on the button labelled CALCULATE to compute the sample size required to represent a sample drawn from a larger population.

Expected Mean Expected
Standard
Deviation		 Zalpha Zbeta Expected
Percent
Difference
Sample Size Numerator Denominator
Click here to return to the Webulator Menu Page
For more information, please contact:

Professor William J. Montelpare, Ph.D.,
Margaret and Wallace McCain Chair in Human Development and Health,
Department of Applied Human Sciences, Faculty of Science,
Health Sciences Building, University of Prince Edward Island,
550 Charlottetown, PE, Canada, C1A 4P3
(o) 902 620 5186


Visiting Professor, School of Healthcare, University of Leeds,
Leeds, UK, LS2 9JT
e-mail wmontelpare@upei.ca
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