3.2 Binary Variables
A large variety of coefficients has been developed for binary data. SPSS CLUSTER (SPSS
2001) provides 27 similarity or dissimilarity measures for binary variables. The measures for
binary variables differ in the following aspects.
1. Conjoint presence (1,1) or (+,+) is weighted differentially.
2. Conjoint absence (0,0) or (-,-) is weighted differentially.
3. Mismatches (1,0) or (0,1) are weighted differentially.
Table 3-1 summarizes some measures using the following numbers and symbols: