# plot.fechner: Plot Method for Objects of Class fechner In fechner: Fechnerian Scaling of Discrete Object Sets

## Description

S3 method to plot objects of the class `fechner`.

## Usage

 ```1 2``` ```## S3 method for class 'fechner' 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.

## 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.

## 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`.

## Author(s)

Thomas Kiefer, Ali Uenlue. Based on original MATLAB source by Ehtibar N. Dzhafarov.

## 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/.

`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.
 ```1 2 3 4 5 6``` ```## 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) ```