1. Suppose now that these curves have been adjusted for screening and demographics, and that the survival improvement is entirely a reflection of technological change (such as the introduction of HAART, an effective AIDS drug that boosts immune function, in 1994). Explain why we do not have enough information in Figure 13.9(a) to determine if the improvements in HIV longevity were cost-effective.
2. Figure 13.9(b) shows that expenditures on HIV treatment rose rapidly during approximately the same period. Is this evidence that the price of HAART was increasing during this time? Is it evidence that the cost of survival was increasing during this time?

TECHNOLOGY AND THE PRICE OF HEALTH CARE 277 (a) HIV survival curves, 1980-2000 0.9 0.8 0.7 0.6 Probability 0.5 0.4 1980 1986 1992 2000 0.3 0.2 0. 1 0 10 20 30 40 50 60 70 80 Years since infection (b) HIV expenditures, 1986-2004 4.5 4 . 3.5 3 2.5 $ billion 2 1.5 - 1 0.5 0 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 Year - Public Private - Total Figure 13.9. Trends in HIV survival and expenditures in the US. (a) HIV survival curves, 1980-2000. (b) HIV expenditures, 1986-2004. Source: Figures 3 and 4 from Philipson and Jena (2006). Reproduced with permission of De Gruyter