There are four important words in the world of B2B research:

A census is great as it gives you a definitive answer to your question – because every single person of interest has inputted, you can have great confidence in the results.  However, conducting a census is usually impractical because the population may be large (thus consulting everyone in it time consuming and costly) and not everyone in it can actually be engaged.

That’s where surveys come in.  They are practical to conduct and give an indication of what you’d be likely to find in the wider population.  But how good an indication of wider opinion does a survey give?  To estimate this, we use a statistical concept called the ‘margin of error’.

The margin of error tells you the extent to which a survey result is likely to match what you’d see in a census.  For example, imagine that 50% of people answer ‘yes’ to a survey question and the margin of error is +/-3%.  This means that the survey result is likely to differ from the result you’d see from the entire population by no more than +3% or -3% (i.e. a census would see a result between 47% and 53%).  The margin of error needs to be considered in conjunction with the ‘confidence level’ which indicates how often the margin of error (which is after all an estimate) will be accurate.  For example, a confidence level of 95% (a common standard used in research) means that the margin of error will hold true in 95 out of 100 cases.

You can use the calculators below to calculate the margin of error.  The first can be used when planning a survey to see what margin of error different sample sizes would bring.  The second can be used post-survey to see the precise margin of error for a particular result.


Predict the margin of error before your survey

Sample size must be greater than 0
Min Max

Calculate the margin of error for a result in your survey

Sample size must be greater than 0
Min Max
Confidence must be a percentage between 1 and 99

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