The PDI distinguishes two qualitatively different forms of purchase-occasion involvement: Product Class Involvement (PCI), reflecting perceived importance and personal relevance of the product category itself, and Brand Decision Involvement (BDI), reflecting concern about selecting the best brand within the category. Mittal (1989) argued that prior involvement scales conflated these constructs: a consumer may be highly involved with a product class but relatively unconcerned about brand decision, or vice versa. PCI predicts depth of category search; BDI predicts comparison shopping, brand attribute evaluation, and brand switching. Particularly useful in services marketing, gift purchasing, and health product research.
5-point Likert (1=strongly disagree to 5=strongly agree); two subscales averaged separately; no composite total
Product Class Involvement — PCI (3 items): perceived importance and personal relevance of the product category. 5-point Likert. Items averaged.
Brand Decision Involvement — BDI (3 items): extent to which the consumer cares about which brand is selected. 5-point Likert. Items averaged.
Full scale items shown. Always cite the original source when using this scale in research.
PCI and BDI should not be summed; report and analyse them separately. PCI is conceptually similar to Bloch et al.'s (1986) EII but is occasion-specific rather than dispositional. Substitute the target product category for '[product]' throughout.
Mittal, B. (1989). Measuring purchase-decision involvement. Psychology & Marketing, 6(2), 147–162.
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