Description Usage Arguments Details Value Author(s) References See Also Examples

This function applies the time series method of Pennington (1986) for estimating relative abundance to a survey series of catch per tow data

1 |

`year` |
vector containing the time series of numeric year labels. |

`index` |
vector containing the time series of mean catch per tow data. |

`logtrans` |
a logical value indicating whether the natural log-transform should be applied to the mean catch per tow values. Default is TRUE. |

`graph` |
a logical value indicating whether a graph of the observed and model fit should be drawn. Default is TRUE. |

Parameters for a first difference, moving average model of order 1 are estimated from the trawl time series using function `arima`

.
Following Equation 4 in Pennington (1986), fitted values are calculated from the model residuals and the estimate of theta.

List containing summary statistics (sample size (n), the first three sample autocorrelations (r1-r3) for the first differenced logged series) and parameter estimates (theta, theta standard error, and sigma2), the observed log-transformed index and fitted values, and the ARIMA function output.

Gary A. Nelson, Massachusetts Division of Marine Fisheries gary.nelson@state.ma.us

Pennington, M. P. 1986. Some statistical techniques for estimating abundance indices from trawl surveys. Fishery Bulletin 84(3): 519-525.

1 2 | ```
data(yellowtail)
surveyfit(year=yellowtail$year,index=yellowtail$index)
``` |

fishmethods documentation built on July 13, 2017, 5:02 p.m.

Embedding an R snippet on your website

Add the following code to your website.

For more information on customizing the embed code, read Embedding Snippets.