Proper and Improper Multiple Imputation

Multiple imputation has become viewed as a general solution to missing data problems in statistics. However, in order to lead to consistent asymptotically normal estimators, correct variance estimators and valid tests, the imputations must be proper . So far it seems that only Bayesian multiple imputation, i.e. using a Bayesian predictive distribution to generate the imputations, or approximately Bayesian multiple imputations has been shown to lead to proper imputations in some settings. In this paper, we shall see that Bayesian multiple imputation does not generally lead to proper multiple imputations. Furthermore, it will be argued that for general statistical use, Bayesian multiple imputation is inefficient even when it is proper.     

Arab socialism in Egypt

The characteristic feature of ‘Arab socialism’, as practised in Egypt, is public ownership of the modern sectors, including finance and trade. Efficiency, in these sectors, and perhaps in agriculture, however, has suffered. Despite some improvement in distribution, following confiscation of larger businesses and rural estates, Egyptian society cannot be considered egalitarian. Egypt's system of agrarian co-operatives is perhaps the only feature of Arab socialism worth imitating.     

Market segmentation,advertising and the concept of communication systems

In this paper, attempts have been made to: (1) examine some of the underlying causes of the difficulties in which the advertising industry finds itself; and (2) to propose a basis for a reconceptualization of the role and function of that industry. The basis proposition is that the advertising industry has failed to evolve strategically because it has become locked into ways of thinking about communication and market segmentation which are inadequate and limiting in some crucial ways. By way of an alternative mode of thinking, it is proposed that natural market segments arise from the manner in which people establish and maintain ways of knowing and acting. Since they do so basically in communication with others, the concept of communication system is proposed as a means of identifying such natural market segments. By segmenting markets into various functioning communication systems (as distinct from purely statistical categorizations) and by formulating advertising strategies accordingly, advertisers are more likely to be able to communicate effectively and less likely to find themselves accused of misleading or irrelevant advertising.     

Mixed Causal–Noncausal Autoregressions: Bimodality Issues in Estimation and Unit Root Testing1

This paper stresses the bimodality of the likelihood function of the Mixed causal–noncausal AutoRegressions (MAR), and it is shown that the bimodality issue becomes more salient as the causal root approaches unity from below. The consequences are important as the roots of the local maxima are typically interchanged, attributing the noncausal component to the causal one and vice‐versa. This severely changes the interpretation of the results, and the properties of unit root tests of the backward root are adversely affected. To circumvent the bimodality issue, this paper proposes an estimation strategy which (i) increases noticeably the probability of attaining the global MLE; and (ii) selects carefully the maximum used for the unit root test against a MAR stationary alternative.     

What You Should Know About Megaprojects and Why: An Overview

This paper takes stock of megaproject management, an emerging and hugely costly field of study, by first answering the question of how large megaprojects are by measuring them in the units of mega, giga, and tera, and concluding with how we are presently entering a new “tera era” of trillion‐dollar projects. Second, total global megaproject spending is assessed, at US$6 to US$9 trillion annually, or 8% of the total global gross domestic product (GDP), which denotes the biggest investment boom in human history. Third, four “sublimes”—political, technological, economic, and aesthetic—are identified and used to explain the increased size and frequency of megaprojects. Fourth, the “iron law of megaprojects” is laid out and documented: Over budget, over time, over and over again. Moreover, the “break–fix model” of megaproject management is introduced as an explanation of the iron law. Fifth, Albert O. Hirschman's theory of the “Hiding Hand” is revisited and critiqued as unfounded and corrupting for megaproject thinking in both the academy and policy. Sixth, it is shown how megaprojects are systematically subject to “survival of the unfittest,” which explains why the worst projects get built rather than the best. Finally, it is argued that the conventional way of managing megaprojects has reached a “tension point,” in which tradition is being challenged and reform is emerging.     

Debt Crises and Risk‐Sharing: The Role of Markets versus Sovereigns

Using a variance decomposition of shocks to gross domestic product (GDP), we quantify the role of international factor income, international transfers, and saving in achieving risk‐sharing during the recent European crisis. We focus on the subperiods 1990–2007, 2008–2009, and 2010 and consider separately the European countries hit by the sovereign debt crisis in 2010. We decompose risk‐sharing from saving into contributions from government and private saving, and show that fiscal austerity programs played an important role in hindering risk‐sharing during the sovereign debt crisis.     

The Return to Direct Investment in Private Firms: New Evidence on the Private Equity Premium Puzzle*

This paper uses a novel dataset to analyze the return to direct investments in private firms by pension funds. We have two key findings. First, direct investments in private firms have underperformed public equity by 392 basis points per annum under conservative risk adjustments. Second, initial mispricing, due to over‐optimism or misperceived risk, and subsequent low capital gains seem to explain the gap in returns to private firms. Overall, these findings complement the finding of Moskowitz and Vissing‐Jørgensen (2002) of low returns on entrepreneurial investments and provide new insight into the existence of what they call the private equity premium puzzle: Even professional investors with well‐diversified portfolios like pension funds seem to get a poor risk‐return tradeoff from investing directly in private firms.     

Piggybacking strategies for nonprofits: A shared costs approach

This article presents case data and a conceptual foundation for nonprofit piggybacking whereby a nonprofit organization subsidizes its deficit producing primary mission by diversifying into related surplus-producing ventures. Shared common and joint costs are considered as supply-side bases for selecting among demand-side related diversification activities.