Description Usage Arguments Details Value References See Also Examples
Generation of Age-Length Keys (ALK) using incomplete data, by the method proposed by Hoenig et al. (1993, 1994).
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Ak |
A list of |
fik |
A list of |
fiz |
A list of vectors of equal length ( |
age_classes |
A vector with the name of each age class. |
length_classes |
A vector with the name of each age class. |
threshold |
The value at which convergence is considered to be achieved: see ‘details’. |
maxiter |
The maximum number of iterations of the EM algorithm: see ‘details’. |
name |
A string with the name of the ALK. |
description |
A string describing the ALK. |
Calculates an ALK using the generalized method proposed by Hoenig et al. (1993, 1994), which uses an undefined number of data sets with known and unknown age information.
The returned ALKr
object contains information on
the convergence threshold that was used, the number of
iterations ran, and if convergence was reached.
The method proposed by Hoenig et al. (1993, 1994) is based on the EM algorithm as defined by Dempster et al. (1997), and it generates the ALK by a series of iterations which are repeated until convergence is acheived.
Let Nz
be a list of matrices containing the number
of fish in each length and age class for each of the
z
populations with unknown age information and
with length distribution specified by fiz
.
Convergence is tested by evaluating the greatest of the
absolute differences between all pairs of Nz
matrices generated on the current and previous
iterations: max(mapply("-", Nz, Nz.old))
.
A list of ALKr
objects, one for each item in the
fiz
list, each containing a matrix with the
probability of an individual of age j
having
length i
, i.e. P(i|j), the vectors of age
and length classes, and information about the method used
to generate the key.
Dempster, A.P., Laird, N.M., Rubin, D.B. (1977). Maximum
Likelihood from Incomplete Data via the EM Algorithm.
Journal of the Royal Statistical Society. Series B
(Methodological), 39/1, 1-38. DOI:
10.2307/2984875
Hoenig, J.M., Heisey, D.M., Hanumara, R.C. (1993). Using Prior and Current Information to Estimate Age Composition: a new kind of age-length key. ICES CM Documents 1993, 10.
Hoenig, J.M., Heisey, D.M., Hanumara, R.C. (1994). A computationally simple approach to using current and past data in age-length key. ICES CM Documents 1994, 5.
inverse_ALK kimura_chikuni hoenig_heisey gascuel
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