Sample Size Calculator: One Proportion Cross-Sectional

Descriptive Prevalence Study based on effect size and absolute precision

Data Input: (Help) (Example)

Input

 

Results

£\

 

 

 

p

N

DEFF

 

 

 

d

 

 

 

 

Note:

Variables

Descriptions

£\

Probability of type I error

p

Prevalence proportion

DEFF

Estimated Effect Size (Usually 1-4)

d

Desired level of absolute precision

N

Required sample size

Help Aids Top

Application: This section illistrates how to determine the minimum sample size for a one proportion cross sectional study.

Procedure:

  1. Enter

a)    Value of £\, the two-sided confidence level

b)    Proportion for disease

c)    DEFF (Effect Size)

d)    d (Absolute precision)

  1. Click the button ¡§Calculate¡¨ to obtain

a)    sample size

  1. Click the button ¡§Reset¡¨ for a new calculation

Formulae:

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Example

Example 1: Assuming that we have population proportion of 0.5 and DEFF of 1. What is the desired sample size when using 5% absolute precision with 95% level of significance?

£\ = 0.05

p = 0.5

DEFF = 1

d=0.05

N = 1.9602*0.5*0.5*1 / 0.052= 385

Reference:

Lemeshow, S., Hosmer Jr., D.W., Klar, J.,and Lwanga S.K. Adequacy of Sample Size in Health Studies. WHO, 1990. Print.

Gorstein J, Sullivan KM, Parvanta I, Begin F. Indicators and methods for cross-sectional surveys of vitamin and mineral status of populations. Micronutrient Initiative (Ottawa) and Centers for Disease Control and Prevention (Atlanta), May 2007, pg 31

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