Some researchers claim vitamin D is immunosuppressive; others argue it activates the immune system. Advocates for vitamin D supplementation insist that various forms of the “vitamin” can be protective against chronic disease, but longer-term studies have failed to confirm these findings [1]. Even among those who support widespread supplementation with the substance, there is wide acknowledgement that the understanding of vitamin D metabolism is “imprecise” [1].
L.R. Karhausen wrote, "Actually, there is no experience of causation: events do not wear their causal credentials on their faces." [2] In this Review, we discuss how the understanding of vitamin D metabolism in chronic disease may be approaching "black box epidemiology."[2]
The question of whether advertising acts as a barrier to entry has been a subject of ongoing controversy in the industrial organization literature. Advertising might disseminate information, thereby increasing market size, and help consumers make rational choices. On the other hand, advertising might merely persuade consumers of product differentiation where none exists. The second type of advertising could act as a barrier to entry. Such a barrier to entry might be profitable to construct if the incumbent has a long period of legal monopoly with a specific date when entry is permitted, as a patented product does in the pharmaceutical industry. Previous work on entry deterrence in the pharmaceutical industry has included advertising to physicians as an explanatory variable in a generic firm’s entry decision. However, the brand’s advertising choice is endogenous in this context, because both advertising before patent expiration and generic entry depend on expected profits in the post-entry period; and hence, both advertising and entry will be affected by the same forces and the same random errors. This paper analyzes the entry decision more carefully by instrumenting for endogenous, pre-expiration, brand advertising. I conclude that brand advertising is not a barrier to entry by generic firms.
In a period where resources for social needs are becoming scarcer, nonprofit organizations are exploring new avenues to generate the resources necessary to sustain and grow their organizations. One of these options is social enterprise œ the use of profitable business ventures as a means to generate unrestricted income.
In many cases, the challenge of creating a successful business from the ground up is larger than many nonprofits are prepared to undertake. Business success largely depends on identifying a viable opportunity, creating a profitable business model, and consistently mastering operational systems and processes. Nonprofit organizations often struggle to identify and exploit such opportunities for financial gain. Although nonprofits may have a clear understanding of the needs in a given community and be able to raise the necessary capital to start a business, they are frequently unable to address the service delivery, marketing, and accountability challenges that all small businesses face.
