GLEANING IN THE FIELD OF DUAL SCALING

Some historical background and preliminary technical information are f irst presented, and then a number of hidden, but important, methodolog ical aspects of dual scaling are illustrated and discussed: normed ver sus projected weights, the amount of information accounted for by each solution, a perfect solution to the problem of multidimensional unfol ding, multidimensional quantification space, graphical display, number -of-option problems, option standardization versus item standardizatio n, and asymmetry of symmetric (dual) scaling. Contrary to the common p erception that dual scaling and similar quantification methods are now mathematically transparent, the present study demonstrates how much m ore needs to be clarified for routine use of the method to arrive at v alid conclusions. Data analysis must be carried out in such a way that common sense, intuition and sound logic will prevail.