fechner (version 1.0-3)

plot.fechner: Plot Method for Objects of Class fechner

Description

S3 method to plot objects of the class fechner.

Usage

"plot"(x, level = 2, ...)

Arguments

x

a required object of class fechner, obtained from a call to the function fechner.

level

an optional numeric, integer-valued and greater than or equal to $2$, giving the level of comparison of the $S$-index and the overall Fechnerian distance $G$.

...

further arguments to be passed to or from other methods. They are ignored in this function.

Value

If the arguments x and level are of required types, and if there are (off-diagonal) pairs of stimuli with geodesic loops containing at least level links, plot.fechner produces a plot, and invisibly returns NULL.

Details

The plot method graphs the results obtained from Fechnerian scaling analyses. It produces a scatterplot of the overall Fechnerian distance $G$ versus the $S$-index, with rugs added to the axes and jittered (amount = 0.01 of noise) to accommodate ties in the $S$-index and $G$ values. The diagonal line $y = x$ is for visual inspection of the deviations of the two types of values.

The level of comparison refers to the minimum number of links in geodesic loops. That is, choosing level $n$ means that comparison involves only those $S$-index and $G$ values that have geodesic loops containing not less than $n$ links.

If there are no (off-diagonal) pairs of stimuli with geodesic loops containing at least level links (in this case a plot is not possible), plot.fechner stops with an error message.

References

Dzhafarov, E. N. and Colonius, H. (2006) Reconstructing distances among objects from their discriminability. Psychometrika, 71, 365--386.

Dzhafarov, E. N. and Colonius, H. (2007) Dissimilarity cumulation theory and subjective metrics. Journal of Mathematical Psychology, 51, 290--304.

Uenlue, A. and Kiefer, T. and Dzhafarov, E. N. (2009) Fechnerian scaling in R: The package fechner. Journal of Statistical Software, 31(6), 1--24. URL http://www.jstatsoft.org/v31/i06/.

See Also

print.fechner, the S3 method for printing objects of the class fechner; summary.fechner, the S3 method for summarizing objects of the class fechner, which creates objects of the class summary.fechner; print.summary.fechner, the S3 method for printing objects of the class summary.fechner; fechner, the main function for Fechnerian scaling, which creates objects of the class fechner. See also fechner-package for general information about this package.

Examples

## Fechnerian scaling of dataset \link{wish}
f.scal.wish <- fechner(wish)

## results are plotted for comparison levels 2 and 5
plot(f.scal.wish)
plot(f.scal.wish, level = 5)