Lessons from an unplanned scientific and academic life

It is salutary, before reaching the middle of one’s eighties, whilst time is still available and memory is still in good order, to review a long life in its highlights, so as to better appreciate the circumstances that shaped and steered that life through its many days. Besides this appreciation, such a review permits a listing of lessons learned through that life, its joys as well as its woes, in the hope that they may be useful to young readers of your story. Like all other such stories, mine was the story of an individual, who lived under unique circumstances and reacted to them in a unique way. My story is best treated in terms of where it was experienced, that being: Malta (1929 to 1952), Oxford (1952 to 1956), Singapore (1956 to 1960), Khartoum (1960 to 1965), and Saskatoon (1965 to the time of writing). Each transition was necessitated by its own circumstance, brought fresh challenges and sustained a global career with few regrets and much personal and professional satisfaction.peer-reviewe

Aggregate worker reallocation and occupational mobility in the United States: 1971-2000

We investigate the evolution and the sources of aggregate employment reallocation in the United States in the 1971-2000 March files of the Current Population Survey. We focus on the annual flows of male workers across occupations at the Census 3-digit level, the finest disaggregation at which a moving worker changes career and relocates to an observationally different technology. We find that the total reallocation of employment across occupations has been strongly procyclical and sharply declining until the early 1990s, before remaining relatively constant in the last decade. To reveal the sources of these patterns, while correcting for possible worker selection into employment, we construct a synthetic panel based on birth cohorts, and estimate various models of worker occupational mobility. We obtain five main results. The cross-occupation dispersion in labor demand, as measured by an index of net employment reallocation, has a strong association with total worker mobility. The demographic composition of employment, more specifically the increasing average age and college attainment level, explains some of the vanishing size and procyclicality of worker flows. High unemployment weakens the effects of individual worker characteristics on their occupational mobility. Worker mobility has significant residual persistence over time, as predicted by job-matching theory. Finally, we detect important unobserved cohort-specific effects; in particular, later cohorts have increasingly low unexplained occupational mobility, which contributes considerably to the downward trend in total employment reallocation over the last three decades.

Occupational Mobility and the Business Cycle

Do workers sort more randomly across different job types when jobs are harder to find? To answer this question, we study the mobility of male workers among three-digit occupations in the matched files of the monthly Current Population Survey over the 1979-2004 period. We clean individual occupational transitions using the algorithm proposed by Moscarini and Thomsson (2008). We then construct a synthetic panel comprising annual birth cohorts, and we examine the respective roles of three potential determinants of career mobility: individual ex ante worker characteristics, both observable and unobservable, labor market prospects, and ex post job matching. We provide strong evidence that high unemployment somewhat offsets the role of individual worker considerations in the choice of changing career. Occupational mobility declines with age, family commitments and education, but when unemployment is high these negative effects are weaker, and reversed for college education. The cross-sectional dispersion of the monthly series of residuals is strongly countercyclical. As predicted by Moscarini (2001)’s frictional Roy model, the sorting of workers across occupations is noisier when unemployment is high. As predicted by job-matching theory, worker mobility has significant residual persistence over time. Finally, younger cohorts, among those in the sample for most of their working lives, exhibit increasingly low unexplained career mobility.occupational mobility, business cycle, synthetic cohorts

Estimating a class of triangular simultaneous equations models without exclusion restrictions

This paper provides a control function estimator to adjust for endogeneity in the triangular simultaneous equations model where there are no available exclusion restrictions to generate suitable instruments. Our approach is to exploit the dependence of the errors on exogenous variables (e.g. heteroscedasticity) to adjust the conventional control function estimator. The form of the error dependence on the exogenous variables is subject to restrictions, but is not parametrically specified. In addition to providing the estimator and deriving its large-sample properties, we present simulation evidence which indicates the estimator works well.

Borrowing Constraints and Credit Demand

This paper investigates the determinants of credit demand in the presence of borrowing constraints for the Chilean economy using a recently collected detailed and innovative data set, the Households Financial Survey. The estimation procedure employed allows for the observed debt to be a function of multiple selection rules and incorporates the endogeneity of income and assets into the debt equation. The paper provides compelling evidence that the relationship between household income and debt, both secured and non secured, is highly non linear. This result has clear implications for the level of household debt in the face of financial deregulation.

Abnormalities of hemoglobin A₂

Hereditary abnormalities of the A. fraction of human hemoglobin may be: (a) structural, in which a genetically determined change in the amino acid composition and sequence of either the alpha or the delta polypetide chains, results in the production of a hemoglobin A variant and (b) quantitative, in which changes in concentration in the hemoglobin A₂ fraction occur as a result of activation or repression of the genes for either the alpha or the delta chains or as a result of the replacement of the normal genes for either of these chains by structurally mutant genes. Because the beta and delta chains of human hemoglobins are linked, a number of conditions also involving the beta chain genes (delta-beta hybrid chain hemoglobins, hereditary persistence of fetal hemoglobin, the beta thalassemias) produce changes in hemoglobin A₂ concentration. Several non-hereditary states have been shown to produce quantitative changes in the hemoglobin A₂ fraction.peer-reviewe

The university of utopia

The “University of Utopia" was Garrod's first public lecture in Malta that was delivered on 3rd November 1917, in the same Aula Magna, where on the 15th December 1916, the University of Malta had honoured him with the degree of Doctor of Medicine. The contents of his talk, in its published pamphlet can be summarized as follows: An introduction regarding the state of University education in Britain, the origin of the University and of the curriculum, the four functions of a University, the curriculum in relation to classical studies versus natural science, whereby in the conclusion he speaks about the need for educational methods, problems of time and money, and the University of Utopia. About two-thirds of the pamphlet is devoted to an analysis of the functions of a University and to the claims of classical studies and natural science as a basis for a University education. According to him “The University of Utopia is a dream. It has never existed and never will exist. It is but an ideal at which it behoves us to aim".peer-reviewe

Sir Archibald Garrod and Malta: a historical occasion recalled

This article features a brief biography of Sir Archibald Garrod (1857-1936), a well known English physician, deeply interested in the chemical and metabolic processes which take place in the healthy and in the diseased human body. He is certainly the honorary graduate of the University of Malta whose ideas and work have had the most far-reaching influence and application in medical science. At the outbreak of First World War, he served as a Consulting Physician to the army and was appointed Knight Commander of the Order of St. Michael and St. George for his devoted services. Garrod's early publications were mainly clinical in character and they included several case reports and a small book on the use of the laryngoscope. He is best known, however, for his absorbing studies on alkaptonuria. In 1916 the University of Malta conferred the honorary degree of M.D. on Garrod, "in recognition of the high qualifications possessed and of the special services rendered by the same eminent professors in the cause of humanity during the war".peer-reviewe

The Thalassemia trait in Malta and Gozo

A description of the method used to detect Thalassemia traits is provided with particular reference to Silvestroni and Bianco (1943), who employed this method of testing in a series of population surveys carried out in Italy and Sicily. Their objective was to the map the geographical pattern of incidence of this anomaly. The same method was then adopted for a survey in Malta and Gozo between 1960 and 1963. The most interesting feature is that the results of the Maltese survey are very similar to those found by Silvestroni and Bianco (1949,1953) in neighboring Sicily.peer-reviewe