ISOLATING THE DETERMINANTS OF INNOVATIVENESS - A SPLIT-POPULATION TOBIT (SPOT) DURATION MODEL OF TIMING AND VOLUME OF FIRST AND REPEAT PURCHASE

The authors present the Split-Population Tobit (SPOT) duration model t o incorporate two conceptually distinct dimensions of innovativeness i n a single framework, namely, the timing and volume of adoption. Rathe r than utilizing a diffusion model specification based on word-of-mout h and social contagion effects, the present approach uses a growth mod el specification and delineates a general function of time to describe the distribution of adoption timing. Estimation and several validatio n exercises performed on a data set describing the diffusion of person al computers across a sample of over 3000 U.S. firms provide strong su pport for the superiority of the SPOT model over models derived from r estricted conceptualizations of innovativeness. The empirical work, al beit modest, tests the impact of covariates, such as firm-size and dec ision-centralization, on the dimensions of innovativeness and sheds li ght on some inconsistent findings in the innovation adoption literatur e. The authors subsequently derive the extended SPOT model (EXT-SPOT) to incorporate repeat purchase volume and timing in the SPOT framework , Finally, they discuss limitations, further research directions, and implications for the practitioner.