# Sampling error

<p>The error caused because <a href="/category/glossary/data">data</a> are collected from part of a <a href="/category/glossary/population">population</a> rather than the whole population.</p>

<p>An <a href="/category/glossary/estimate">estimate</a> of a <a href="/category/glossary/population-parameters">population parameter</a>, such as a <a href="/category/glossary/sample-mean">sample mean</a> or <a href="/category/glossary/sample-proportion">sample proportion</a>, is different for different <a href="/category/glossary/sample">samples</a> (of the same size) taken from the population. Sampling error is one of two reasons for the difference between an estimate and the true, but unknown, value of the population parameter. The other reason is <a href="/category/glossary/non-sampling-error">non-sampling error</a>.</p>

<p>The error for a given sample is unknown but when sampling is <a href="/category/glossary/random-sampling">random</a>, the size of the sampling error can be estimated by calculating the <a href="/category/glossary/margins-error">margin of error</a>.</p>

<p>See: <a href="/category/glossary/margins-error">margin of error</a>, <a href="/category/glossary/non-sampling-error">non-sampling error</a></p>

<p><strong>Curriculum achievement objectives references</strong><br />

Statistical investigation: Levels (5), (6), (7), (8)<br />

Statistical literacy: Levels 7, (8)</p>