Given a sample, the value of the computed sample statistic gives a
**point estimate** of the corresponding population
parameter. For example, the sample mean \((\bar x)\) is a point estimate of the
corresponding population mean \((\mu)\), or the sample standard deviation
\((s)\) is a point estimate for the
population standard deviation \((\sigma)\). However, one should note that
any randomly selected sample from a population is expected to yield a
different value of the sample statistic (sampling error). In other words, the sample mean
\(\bar x\) and the sample standard
deviation \(s\) will vary from sample
to sample, whereas the population mean \(\mu\) and the population standard deviation
\(\sigma\) are fixed. Consequently, the
point estimate almost always differs from the true value of the
population. Therefore, any point estimate should be accompanied with
information that indicates the accuracy of that estimate.

**Citation**

The E-Learning project SOGA-R was developed at the Department of Earth Sciences by Kai Hartmann, Joachim Krois and Annette Rudolph. You can reach us via mail by soga[at]zedat.fu-berlin.de.

You may use this project freely under the Creative Commons Attribution-ShareAlike 4.0 International License.

Please cite as follow: *Hartmann,
K., Krois, J., Rudolph, A. (2023): Statistics and Geodata Analysis
using R (SOGA-R). Department of Earth Sciences, Freie Universitaet Berlin.*