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# Sample Calculator

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: Assumes 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:

• Choose a confidence level
• Enter an acceptable margin of error (between .1 and 50 – leave off % sign)
• Enter population (if known)
Click on “calculate”
• 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 Calculator

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: Assumes 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:

• Choose a confidence level
• Enter an acceptable margin of error (between .1 and 50 – leave
off % sign)
• Enter population (if known)
Click on “calculate”
• 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.

to discuss other possible sources of bias (i.e. question bias).

 Confidence Level: 95% 99% Margin of Error/Confidence Interval: (Do not include % sign) Population: Sample size needed:

(This sample size calculator was created by Creative
Research Systems
.)

 Sample Size: n= 50 100 200 300 400 600 800 1,000 Margin of Error*:(+/-) 14.2% 10.0% 7.1% 5.8% 5.0% 4.1% 3.5% 3.2%

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 Riley Research.