About Surveys

One of the most asked questions in surveys and sampling is "what should my sample size be?"  It is definitely important and there are several factors that need to be taken into account before a sample size is determined.  These factors are:

The level of precision

The confidence level

Degree of Variability

There are several strategies in determining a sample size:

Use a Census for small populations

Use a Sample Size of a similar study

Use Published tables

Use a formula

There are actually several formulas that can be used to determine sample size.   They are all variations of the same princple formula.  A simple formula that will almost always be effective in determining a proper sample size is:

n=(N/(1+N(e)^2))

where:

n=sample size

N=Population size

 e=margin of error

This entry was posted by craigl on Wednesday, May 21st, 2008 at 9:45 am and is filed under Create Surveys.