Sample Size Calculator - Hover over definitions
This is the level of certainty with which you will estimate the true population value. You can select either 95% or 99%.
This is the total number of individuals or groups about which information is required.
This specifies the expected proportion of the population to have the attribute that you are estimating from your survey. You can get the proportion from previous cycles of the survey or by an educated guess. If this proportion is unknown, it should be set to 0.5 (i.e. 50%), as this produces a conservative estimate of variance.
This allows you to specify the desired level of accuracy of the estimate. The confidence interval value is expressed as a proportion, meaning that if you want the result to be accurate within 5 percentage points, then you should enter 0.05.
Confidence Interval: Upper and Lower
These are the upper and lower bounds of the confidence interval, as determined by the specified interval. For example, if the proportion os 0.5 and the specified confidence Interval is 0.05, then the upper and lower bounds will be 0.5 +/- 0.05, which gives you a confidence interval from 0.45 to 0.55.
This is a measure of sampling error that indicates the degree to which an estimate may vary from the true value.
Relative Standard Error
This is the standard error expressed as a percentage of the estimate.
This refers to the number of individuals or groups required to respond (not just the number approached) to achieve the required level of accuracy.
For a more detailed explanation of what each of these categories mean see Sample Size Calculator Help