compare2: Comparisons of two age readers or two aging methods

In fishmethods: Fishery Science Methods and Models

Comparisons of two age readers or two aging methods

Description

Function compares graphically the readings of two age readers and calculates 2 chi-square statistics for tests of symmetry.

Usage

 compare2(readings, usecols = c(1,2), twovsone = TRUE, plot.summary = TRUE, 
  barplot = TRUE, chi = TRUE, pool.criterion = 1, cont.cor = TRUE, 
  correct = "Yates", first.name = "Reader A",second.name = "Reader B")

Arguments

readings	dataframe or matrix containing the readings by Reader 1 and those by Reader 2.
usecols	columns of the dataframe or matrix corresponding to the readings of Reader 1 and those of Reader 2. Default=c(1,2).
twovsone	logical for whether first type of graph is produced.
plot.summary	logical for whether summary table is put on first graph.
barplot	logical for whether barplot of frequency of disagreements is drawn.
chi	logical for whether 2 chi-square tests are performed.
pool.criterion	used to collapse pairs where the expected number of observations is < pooling criterion (default is 1).
cont.cor	logical for whether a continuity correction should be used in 1st chisquare test.
correct	character for whether "Yates" or "Edwards" continuity correction should be done (if cont.cor=TRUE).
first.name	character string describing the first reader or the first aging method. The default is to specify "Reader A".
second.name	character string describing the second reader or the second aging method. The default is to specify "Reader B".

Details

This function can plot the number of readings of age j by reader 2 versus the number of readings of age i by reader 1 (if twovsone=TRUE). Optionally, it will add the number of readings above, on, and below the 45 degree line (if plot.summary=TRUE). The function can make a histogram of the differences in readings (if barplot=TRUE). Finally, the program can calculate 2 chi-square test statistics for tests of the null hypothesis that the two readers are interchangeable vs the alternative that there are systematic differences between readers (if chi=TRUE). The tests are tests of symmetry (Evans and Hoenig, 1998). If cont.cor=T, then correction for continuity is applied to the McNemar-like chi-square test statistic; the default is to apply the Yates correction but if correct="Edwards" is specified then the correction for continuity is 1.0 instead of 0.5.

Value

Separate lists with tables of various statistics associated with the method.

Author(s)

John Hoenig, Virginia Institute of Marine Science, 18 December 2012. [e-mail]

References

Evans, G.T. and J.M. Hoenig. 1998. Viewing and Testing Symmetry in Contingency Tables, with Application to Fish Ages. Biometrics 54:620-629.).

Examples

 data(sbotos)
 compare2(readings=sbotos,usecols=c(1,2),twovsone=TRUE,plot.summary=TRUE,
 barplot=FALSE,chi=TRUE,pool.criterion=1,cont.cor=TRUE,correct="Yates",
 first.name="Reader A",second.name="Reader B")

fishmethods documentation built on April 27, 2023, 9:10 a.m.