Advances in multidimensional unfolding

On the 21st of April 2010, Frank Busing defended his PhD Thesis on Advances in Multidimensional Unfolding. Busing was born in Amsterdam, graduated in 1983 from the Fioretti College in Lisse and studied Child and Education Studies (propedeuse 1987) and Psychology (degree in 1993) at Leiden University. In 2000 he received his qualification to teach at primary schools from the Hogeschool IPABO in Amsterdam

What does multidimensional unfolding entail?

Figure 1: Unfolding solution for the Breakfast Data (Green and Rao, 1972), where the dots represent respondents, small distances to the items correspond to high preferences, and vise versa.

Figure 1: Unfolding solution for the Breakfast Data (Green and Rao, 1972), where the dots represent respondents, small distances to the items correspond to high preferences, and vise versa.

Busing implemented PROXSCAL, a programme for multidimensional scaling (proximity scaling), in SPSS, after which he started his research on unfolding analysis. Since its conception in the early sixties, unfolding was cursed with the so-called degeneracy problem, a stubborn problem causing perfect but worthless solutions. It took five years to get the current satisfactory solution published. Soon after that, it was also implemented in SPSS as PREFSCAL (preference scaling). The remainder of his thesis consists of overdue unfolding research and an unreadable technical appendix, describing the mathematical details of PREFSCAL. According to Busing, unfolding is one of the most beautiful analysis techniques: It allows ordinal data to be represented as distances between locations in a configuration, a graphical result that can be interpreted by anyone (see Figure 1).  


The past

Most of the time during his PhD research, Busing was a teacher at the primary school Oostelijke Eilanden in Amsterdam. Combining both worlds was both stimulating and exhausting. After becoming a husband to Afke, a fresh resident of Alkmaar, a father to foster child Suraj, a boss for Kees (a Friese Stabij), and a father again of newborn Bonne, keeping both jobs became an unbearable situation. Busing opted for Leiden University.    

The Future

Currently, Busing teaches statistics to first year psychology students, offers statistical advice to master students (Masters Thesis Lab), and continues his research on extensions and improvements of unfolding. When asked what advice he would give starting PhD students he says: make sure you enjoy the process as much as the product and keep momentum.

Last Modified: 18-04-2011