Forty million people are infected with HIV worldwide; twenty-five million of them are in Sub-Saharan Africa. This paper addresses the question of why Africa has been so heavily affected by HIV, and what explains the variation within Africa. I present a model that decomposes epidemic level into differences in sexual behavior and differences in viral transmission rates. I argue, using evidence drawn from the existing medical literature, that Africa has very high HIV transmission rates, likely due to high rates of other untreated sexually transmitted infections, while transmission rates in the United States are low. The difference in transmission rates is large enough to explain the observed difference in prevalence between the United States and Sub-Saharan Africa. The model also provides a good fit to cross-country data within Africa and suggests that, in contrast to the intra-continental results, differences within that continent can be attributed to differences in sexual behavior and epidemic timing. The results suggest that cost-effective policy interventions would focus on decreasing transmission rates within Africa, possibly by treating other untreated sexually transmitted infections.

Whereas macroprudential policy has come to the fore since the Global Financial Crisis, with many regulators being given responsibility for such policy, the appropriate tools and the effectiveness of such tools remain open questions. We suggest that existing work on effectiveness of macroprudential policy may be vulnerable to bias due to omission of long run cointegration effects. This paper seeks to offer a fresh baseline for work in this area by adopting a cointegration framework which is robust to a variety of alternative techniques and compares favourably with non-cointegrated alternatives. We assess the impact of typical macroprudential policy interventions on house price and household credit growth in up to 19 OECD countries, using three datasets from the IMF and BIS, thus giving both a wider range of control variables and broader coverage of instruments than in most extant work. We find evidence that macroprudential polices remain effective in both short- and long-run at curbing house price and household credit growth even within a cointegration framework, albeit some tools are more effective than others. These include, in particular, taxes on financial institutions, general capital requirements, strict loan-to-value ratios and debt-to-income ratio limits.

Using exogenous shocks on the ability to issue seasoned equity offerings (SEOs), we show SEOs lead to a higher employee skill composition, that is, a lower (higher) proportion of low (high) skilled workers. The decrease in low-skilled workers exceeds the increase in high-skilled workers, resulting in reduced employment at the firm level. These effects are more significant when firms invest more in technology following SEOs and face greater financial constraints before SEOs, suggesting that SEOs relieve budget constraints on technology investments. These findings demonstrate that while external equity financing helps upgrade technology to improve productivity, it has a dark side for low-skilled workers.

We propose a model of limited arbitrage based on financial relationships. Financially constrained arbitrageurs may choose to seek additional financing from banks that have the technology to profit from the strategies themselves. A holdup problem arises because banks cannot commit to providing capital. To minimize competition, arbitrageurs will choose to stay constrained and underinvest in the arbitrage unless banks have sufficient reputational capital. This problem arises when mispricing is largest. More competition among financiers, higher arbitrageur wealth, and allowing for explicit contracts can worsen the holdup problem. When arbitrage is risky, financial relationships are more valuable, mitigating the problem.

This paper investigates tax effects in the Canadian government bond market during the period 1964—1986. Unlike previous studies, we apply both statistical and nonstatistical teststo analyze clientele effects and market equilibria. The results divide the sample into two distinct periods of time, with the end of 1976 marking the division. We find that tax effects are almost nonexistent in the Canadian government bond market before the end of 1976, but are predominant in the post-1976 period. Non-segmented market equilibria cannot be rejected before 1977, but are strongly rejected after 1976. In fact, segmented equilibria with clientele effects in both quantities and prices characterize the entire five year period from 1982 to 1986. These findings are consistent with tax reforms, government deficit financing and interest rate fluctuations in Canada during our sample period.

Screening potential investments involves dividing a set of companies into those that are suitable to consider for investment and those that are less desirable (Kinder 2005). In this paper, I document that nonprofessional investors (represented by MBA students) are susceptible to scale compatibility effects when implementing an investment screen using non-financial measures. Such effects occur when investors rely more on a scale compatible non-financial measure whose values directly map into investors' judgments than on an equally relevant but scale incompatible measure whose values do not map into their judgments. Results from an experiment indicate that investors reduce their susceptibility to scale compatibility effects when they simultaneously screen several companies for potential investment. Because screening investments involves screening several companies, simultaneous screening represents an efficient mechanism to de-bias scale compatibility effects.

Paul Samuelson's Foundations of Economic Analysis played a major role in defining how economic theory was undertaken for many years after the Second World War. This paper fills out Samuelson's account of the book's origins and corrects some details, making clear his debt to E. B. Wilson and establishes that turning the thesis into a book was a long process. The contents of the book and its reception are then reviewed.

This paper is concerned with situations where firms not only recognize the dependence of quality on price (of productivity on wages, of default probability on the interest rate charged), but also attempt to use what control they have over price (wages, interest rates) to increase their profits. The recognition of this possibility has important implications for economic theory, which have recently been explored in a large number of papers in several disparate fields. The objective of this paper is to survey these papers and to draw out the central themes of this literature. This paper is divided into four parts, In Part I, we discuss the most important implications of the dependence of quality on price for competitive equilibrium theory--the repeal of the law of supply and demand (Part I.1), the repeal of the law of the single price (Part I.2), the existence of discriminatory equilibria (Part I.3), the comparative static consequences (Part I.4), and the inefficiency of market equilibria (Part I.5). Part II discusses alternative explanations for the dependence of quality on price in labor, capital, and product markets.