mohn | R Documentation |
Calculate Mohn's rho, the average relative bias of retrospective estimates.
mohn(x, peels = 5, details = FALSE, plot = FALSE, ...)
x |
a matrix or data frame containing retrospective estimates in columns, with years as row names. |
peels |
the number of retrospective peels to use in the calculation of
rho, or |
details |
whether to return the intermediate calculations of relative bias. |
plot |
whether to plot the retrospective trajectories. |
... |
passed to |
The default value peels = 5
is based on the ICES (2018) guidelines.
The basic plot = TRUE
functionality is intended to quickly visualize
the calculation of Mohn's rho. To produce a fully formatted plot, bypass the
mohn
function and plot the x
data directly.
Mohn's rho, along with intermediate calculations if details = TRUE
.
Relative bias is defined as
b_i=\frac{\hat\theta^{R_i}_{T\!-i}\,-\,\hat\theta_{T\!-i}}{\hat\theta_{T\!-i}}
and Mohn's rho is the average relative bias:
\rho=\sum_{i=1}^n\frac{b_i}{n}
See Mohn (1999), Brooks and Legault (2016), ICES (2018), and
mohn(shake, details=TRUE)
for details.
Arni Magnusson, with a contribution from Ruben Verkempynck.
Brooks, E.N. and Legault, C.M. (2016). Retrospective forecasting — evaluating performance of stock projections in New England groundfish stocks. Canadian Journal of Fisheries and Aquatic Sciences, 73, 935–950. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1139/cjfas-2015-0163")}.
ICES (2018). Guidelines for calculating Mohn's rho: Retrospective bias in assessment. Draft document version 7 (2018-04-03), available at the Expert Groups area on the ICES Sharepoint.
ICES (2020). Workshop on Catch Forecast from Biased Assessments (WKFORBIAS; outputs from 2019 meeting). ICES Scientific Reports 2(28). \Sexpr[results=rd]{tools:::Rd_expr_doi("10.17895/ices.pub.5997")}.
Mohn, R. (1999). The retrospective problem in sequential population analysis: An investigation using cod fishery and simulated data. ICES Journal of Marine Science, 56, 473–488. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1006/jmsc.1999.0481")}.
shake
is a retrospective example table.
icesAdvice-package
gives an overview of the package.
mohn(shake)
mohn(shake, details=TRUE)
mohn(shake, plot=TRUE)
mohn(shake, peels=3, plot=TRUE, col="black", ylim=0:1, yaxs="i")
lines(as.numeric(rownames(shake)), shake$base, lwd=3)
## Plot last 10 years
x <- rbind(matrix(1,28,6,dimnames=list(1981:2008,names(shake))), shake)
mohn(tail(x, 10), plot=TRUE, lwd=2, main="main")
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