[2] In the model, health enters the utility function directly as a good people derive pleasure from and indirectly as an investment which makes more healthy time available for market and non-market activities.
When the partial derivative of the utility function with respect to health consumption is assumed to equal zero, the resulting sub-model is the investment model.
[10] Similarly, critics of Grossman's model have conceptualized the issue not from the point of view of healthcare demand, but the avoidance of illness which in itself is a disutility.
In another departure from Grossman's model on the question of expenditures and demand over time, University of Maryland Economics professor Maureen Cropper argues that healthcare demand should be delineated between preventative care and treatment of illness, the latter of which is often correlated with end of life treatment and can be seen as more random based on illness occurrence.
[13] Additionally, researchers have questioned the independence of the individual variables in the model such as education, income, as well as socioeconomic and occupation status.
[14] Particular attention had been paid to riskier professions, which generally entail higher wages due to occupational hazards and thus make such variable co-dependent.
[15] Much to the same point, Dr. Victor Fuchs argues that both genetic and gendered differences operate as unobserved, immutable variables within the model.