The following data was obtained by Rothkopf (1957) using 598 individuals who were asked to judge whether a pair of consecutively presented Morse code singals were identical or not. Using the pairwise comparisons similarity data matrix of proportions, we wish to discern a possible ordering, in a space of smaller dimension, of correctly identified (incorrectly confused) Morse code signals:
(a) Carry out a principal components analysis of the similarity matrix.
(b) Carry out a maximum likelihood factor analysis using information obtained from part a.
(c) Compare the two analyses with each other, as well as to Shepard's (1963) multidimensional scaling analysis of the data.