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How
many people do you need to talk to to get a
margin of error you are comfortable with? Consult our handy calculator and
find out!
Listed
below are few terms you will need to understand before using the sample
size calculator:
Confidence
Level:
The percentage value that tells how confident a researcher can be about
being correct. A 95% confidence level is a generally acceptable level of
confidence and is most typically used and accepted within the research
industry. Which means that if a study were conducted 100
times, answers would be within the margin of error 95 out of 100 times.
Margin
of Error / Confidence Interval: Assu.mes that you have a random
sample. The margin of error for a typical survey is +/- 5%. This means that
results may vary as much as five percent in either direction. The margin of
error for sub-samples (i.e. men versus women), is based on the number in
that sub-sample.
Population
Size:
The
population size is the universe from which you are taking your sample. If
the population size is very large or unknown, leave this field blank.
DIRECTIONS:
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Choose a confidence level
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Enter an acceptable margin
of error (between .1 and 50 - leave off % sign)
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Enter population (if
known)
Click on "calculate"
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This calculator requires
Internet Explorer 3.0 or later or Netscape 3.0 or later or a
compatible browser. Leave the population box blank, if the population
is very large or unknown.
CAUTION:
Sampling error is only one source of bias. Contact us to discuss other possible
sources of bias (i.e. question bias).
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Sample Size: n=
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50
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100
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200
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300
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400
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600
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800
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1,000
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Margin of Error*:(+/-)
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14.2%
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10.0%
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7.1%
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5.8%
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5.0%
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4.1%
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3.5%
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3.2%
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The margin of error for a poorly designed survey:
+/- 100%
*
Based on a 95% level of confidence; assumes a random sample and worst-case
(50/50) response. If this does not make sense, it's time to call
DNA Consulting.
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