SPAS: Stratified-Petersen Analysis System

The Stratified-Petersen Analysis System (SPAS) is designed to estimate abundance in two-sample capture-recapture experiments where the capture and recaptures are stratified. This is a generalization of the simple Lincoln-Petersen estimator. Strata may be defined in time or in space or both, and the s strata in which marking takes place may differ from the t strata in which recoveries take place. When s=t, SPAS reduces to the method described by Darroch (1961) <>. When s<t, SPAS implements the methods described in Plante, Rivest, and Tremblay (1988) <>. Schwarz and Taylor (1998) <doi:10.1139/f97-238> describe the use of SPAS in estimating return of salmon stratified by time and geography. A related package, BTSPAS, deals with temporal stratification where a spline is used to model the distribution of the population over time as it passes the second capture location. This is the R-version of the (now obsolete) standalone Windows program available at <>.

Version: 2019.2
Imports: BB, MASS, Matrix, msm, numDeriv, plyr
Suggests: knitr, rmarkdown
Published: 2019-02-18
Author: Carl James Schwarz
Maintainer: Carl James Schwarz < at>
License: GPL-2 | GPL-3 [expanded from: GPL (≥ 2)]
NeedsCompilation: no
Materials: README NEWS
CRAN checks: SPAS results


Reference manual: SPAS.pdf
Vignettes: Conne River 1991 Data
Conne River 1992 Data
Harrison River Female Chinook 2011 Data
Package source: SPAS_2019.2.tar.gz
Windows binaries: r-devel:, r-release:, r-oldrel:
OS X binaries: r-release: SPAS_2019.2.tgz, r-oldrel: SPAS_2019.2.tgz


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