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Biology: (Bio)statistics

Biostatistics title block

Biostatistics, definition:

Statistics applied to the living world. It includes demography, epidemiology, and clinical trials. Specialized measurement techniques include capturerecapture methods and the analysis of line transects.

Upton, G., & Cook, I. (2014). biostatistics. In A Dictionary of Statistics. : Oxford University Press. 


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Methods in biostatistics

Capture–recapture method 

A method for estimating the size of a population. The method is generally applied to living organisms, such as fish in a lake.

The simplest example proceeds as follows. A sample of n1 individuals is obtained from the population (for example, by catching fish in a net). Each of these individuals is now marked in some fashion (for example, by attaching a tag) and is returned to the population. Later, a second sample (of n2 individuals) is taken from the population. Suppose mof these individuals are tagged. The sample proportion of tagged individuals is m/n2, and the population proportion is n1/N, so that an estimate of the population size, N, is N̂, given by 

This estimate is known as the Petersen estimator of the population size. An alternative that avoids the problem caused when m is zero is provided by the Chapman estimator:

From: Upton, G., & Cook, I. (2014). capture–recapture method. In A Dictionary of Statistics. : Oxford University Press. Retrieved 15 Aug. 2023, from

Line transects

A path, usually straight, across a region of interest, that will be used for sampling. If the path has constant width then the sampling procedure may be to count the organisms in predefined regions of the path (for example, in a sequence of quadrats). Alternatively, the sampler may walk along the line transect either counting visible organisms or recording their positions.

Upton, G., & Cook, I. (2014). line transect. In A Dictionary of Statistics. : Oxford University Press. Retrieved 15 Aug. 2023, from