Species Abundance Models

This menu provides a range of distributions and models that can be used to describe species abundance data. For the log-series, Poisson-log-Normal and negative binomial distributions the species abundance data are grouped into 'octaves' using a logarithmic scale. These distributions are then fitted using the DISTRIBUTION directive using the octave classes. The geometric series, Zipf and Zipf-Mandelbrot models are fitted to the observed abundance data using the non-linear regression facilities. See the ECFIT procedure for further details about the available distributions and models.

Data format

Specifies to format of the data for the plot. Select Single variate to supply the individuals in a single variate. Alternatively, select Multiple variates, if the data are to be supplied in multiple samples of individuals.

Individuals

A variate containing the numbers of individuals per species.

Species

A variate containing the number of species for the associated number of individuals in the corresponding element of Individuals. This field can be left empty if each of the values in Individuals corresponds to one species.

Groups

A factor specifying the groups for different samples.

Samples

For multiple samples this allows you to specify one or more variates containing the individuals for different samples. Multiple selections can be transferred from the Available data list by clicking the

button.

Model

Controls the distribution or model that is to be fitted to the data. You can choose from Log-series, Poisson-log-Normal, negative binomial, Zipf, Zipf-Mandelbrot and Geometric series. See the ECFIT procedure for further details about the available distributions and models.

Available Data

This lists data structures appropriate to the current input field. The contents will change as you move from one field to the next. Double-click on a name to copy it to the current input field; alternatively, you can type the name directly into the input field.