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The random sampling theory estimator of Jolly and Hampton (1990)

Source: R/JollyAndHampton1990.R
jhF.Rd

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.

Usage

jhF(
  transectLength,
  transectMeanDen,
  transectName = NULL,
  svyName = NULL,
  area = NULL
)

Arguments

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.

Value

two element list. $summaryStats and $transects. See details

Details

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.

References

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.

See also

jhMultipleStrataF

Examples

if (FALSE) {
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)
}