View source: R/JollyAndHampton1990.R
jhF | R Documentation |
The Jolly and Hampton (1990) estimator is often used to calculate mean pelagic animal densities and associated variances. Users are encouraged to review Jolly and Hampton (1990) before using this function.
jhF(
transectLength,
transectMeanDen,
transectName = NULL,
svyName = NULL,
area = NULL
)
transectLength |
[numeric, vector] of transect lengths |
transectMeanDen |
[numeric, vector] transect weighted mean densities. See details. |
transectName |
=NULL Optional character vector of transect names. |
svyName |
=NULL Optional character variable of survey names. Must be used if the jhMultipleStrataF function is used to estimate mean and variance across multiple strata. |
area |
=NULL Optional variable of the survey or stratum area. Must be used if the jhMultipleStrataF function is used to estimate mean and variance across multiple strata. |
The transectMeanDen
In the case of acoustic data, each element (areal density value) is multiplied by the integration interval (along transect) length. The distance multiplication must take place outside of this function.
The function returns a two element list. The first element $summaryStats
is a vector with names $svy
- the survey name; MeanWeightedDensity - mean
density as per Jolly and Hampton (1990) $variance
- variance calculated as per Jolly and Hampton (1990), and $totalTransectLength
total transect length. If survey area is provided area
then biomass $biomass
with confidence internal $lowerIntervalBiomass
and $upperIntervalBiomass
. The secord element of the list returned in $transects
statistics fo each trasect.
two element list. $summaryStats
and $transects
. See details
Jolly, G. M., and Hampton, I. 1990. A stratified random transect design for acoustic surveys of fish stocks. Canadian Journal of Fisheries and Aquatic Sciences, 47: 1282-1291.
jhMultipleStrataF
## Not run:
tLengths=c(77.67,78.28,78.91,80.22,78.07,73.60,78.53,78.39,78.52,79.48)
denV=c(158.03,159.50,96.41,133.86,246.60,243.95,122.65,276.92,59.83,89.90)
svyA=80*100*1e6
jhF(transectLength=tLengths,
transectMeanDen=denV,
transectName=NULL,svyName='test',area=svyA)
## End(Not run)
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