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Oct
26 2011

How Many Respondents Do I Need?

Syndicated from: Bramm Research Blog

I am frequently asked by clients, “what sample size do we need”?  In a previous blog I redirected this question to focus on the importance of response rate.  But here I’m going to tackle the question of sample size. Recently I’ve discovered a handy table (Thank you Survey Monkey) for calculating the sample size required at three different error levels for various population sizes.  Okay, let me explain that last statement.  In a lot of survey research we are using a sample to make projections to a very large population e.g. all Canadian adults.  In this situation we can readily calculate a margin of error for different sample sizes.  However, when we’re dealing with a finite population e.g. members of an association, we need to use a slightly different formula to calculate the margin of error.  In a nutshell, when my total population decreases, the sample size required for a specific margin of error also decreases. The following link will take you to the aforementioned table.  This will be of benefit whether your association has 500 members or 100,000 members. http://svy.mk/onjQdE

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