Ages of American Shad assigned from scales by three readers at two times.

Ages of American Shad (Alosa sapidissima) assigned from scales by three readers at two times.

Format

A data frame with 53 observations on the following 8 variables.

fishID

A unique fish identification number

trueAge

The true age of the fish

agerA1

Ages assigned by reader A at time 1

agerA2

Ages assigned by reader A at time 2

agerB1

Ages assigned by reader B at time 1

agerB2

Ages assigned by reader B at time 2

agerC1

Ages assigned by reader C at time 1

agerC2

Ages assigned by reader C at time 2

Source

From McBride, R.S., Hendricks, M.L., and Olney, J.E. 2005. Testing the validity of Cating's (1953) method for age determination of American Shad using scales. Fisheries, 30:10-18. Obtained directly from Rich McBride. CSV file

Details

The true ages for fish in their sample were known because the Shad had been marked prior to being stocked. Additionally, 13 biologists twice (independently) estimated the age from scales for each fish. The known age of the fish (trueAge) and the age estimates from three of the 13 biologists are available in this data.frame. The estimated age variables are labeled with ager, a letter for the three biologists (A, B, or C) and a number for which time the scale was interpreted (1 or 2). Some biologists chose not to assign an age to some scales and, thus, those data are missing (shown as NA values).

Note

Used in the Introductory Fisheries Analyses with R book.

Topic(s)

• Age Comparison

• Age Precision

• Age Bias

• Ageing Error

Examples

data(ShadCR)
str(ShadCR)
#> 'data.frame':	53 obs. of  8 variables:
#>  $ fishID : Factor w/ 53 levels "00-LR2","00-LR20",..: 1 2 10 24 11 16 42 46 17 5 ...
#>  $ trueAge: int  5 4 6 8 6 7 6 3 7 5 ...
#>  $ agerA1 : int  5 3 5 6 5 6 6 4 7 5 ...
#>  $ agerA2 : int  3 3 5 6 5 6 6 3 6 6 ...
#>  $ agerB1 : int  NA 5 NA 6 NA NA 5 NA NA 5 ...
#>  $ agerB2 : int  NA 4 NA 6 NA NA 6 NA NA 5 ...
#>  $ agerC1 : int  4 2 6 5 5 3 3 4 5 2 ...
#>  $ agerC2 : int  3 2 6 3 4 4 3 3 5 3 ...
head(ShadCR)
#>    fishID trueAge agerA1 agerA2 agerB1 agerB2 agerC1 agerC2
#> 1  00-LR2       5      5      3     NA     NA      4      3
#> 2 00-LR20       4      3      3      5      4      2      2
#> 3 01-LR30       6      5      5     NA     NA      6      6
#> 4 03-3571       8      6      6      6      6      5      3
#> 5 01-LR37       6      5      5     NA     NA      5      4
#> 6 02-LR32       7      6      6     NA     NA      3      4
op <- par(mfrow=c(2,2),pch=19)
plot(agerA1~agerA2,data=ShadCR)
plot(agerB1~agerB2,data=ShadCR)
plot(agerC1~agerC2,data=ShadCR)
plot(agerA1~agerB1,data=ShadCR)

par(op)