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title: "Parameters of a population"
canonical: "https://modelassist.epixanalytics.com/space/EA/26574964/Parameters%20of%20a%20population"
format: markdown
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In principle, descriptive parameters can be calculated for a population providing one knows the necessary values for each individual in a population. This is obviously more practical for smaller populations like employees in a small company than large populations like population of a country.


For a fixed population, the descriptive parameter doesn't change. In reality, many populations are dynamic and their descriptive parameters will change accordingly. We will use the height of a population of people as our variable in the examples below:


| **Parameter** | **Description** | **Definition** |
| --- | --- | --- |
| Percentiles x<sub>P</sub> | P% of population are shorter than x<sub>P</sub> |  |
| **Location** |  |  |
| Mode | The most common height (assumes height scale is incremental, not continuous) |  |
| Median x<sub>50</sub> | 50% of population is shorter than x<sub>50</sub> |  |
| Mean *m* | The average height of the population | > Macro (inline-media-image)

> Macro (mathinline) |
| **Spread** |  |  |
| Standard deviation *s* | The square root of the population variance | > Macro (inline-media-image)

> Macro (mathinline) |
| Variance V | The average squared deviation of height from the population height mean | > Macro (inline-media-image)

> Macro (mathinline) |
| Mean absolute deviation | The average difference in height between individuals and the population mean | > Macro (inline-media-image)

> Macro (mathinline) |




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