Revisiting retesting in the estimation of proportions by group testing

In the estimation of a proportion p by group testing (pooled testing), retesting of units within positive groups has received little attention due to the minimal gain in precision compared to testing additional units. If acquisition of additional units is impractical or too expensive, and testing is not destructive, we show that retesting can be a useful option. We propose the retesting of a random grouping of units from positive groups, and compare it with nested halving procedures suggested by others. We develop an estimator of p for our proposed method, and examine its variance properties. Using simulation we compare retesting methods across a range of group testing situations, and show that for most realistic scenarios, our method is more efficient.     

Analysis of child labour in Peru and Pakistan: A comparative study

This paper analyses child labour participation and its key determinants using data sets from Peru and Pakistan. The results include tests of the ‘Luxury’ and ‘Substitution’ hypotheses that play key roles in recent studies on child labour and child schooling. The results reject both hypotheses in the context of child labour in Pakistan and suggest that income and related variables do not have the expected negative effect on children's work input. Rising wages of adult female labour in Pakistan, and falling adult male wage in Peru lead to increased participation of children in the labour market. The results on the combined country data formally establish the presence of strong individual country effects in the estimated regressions. For example, ceteris paribus, a Peruvian child is more likely to experience schooling than a Pakistani child. However, both countries agree on the positive role that adult female education and infrastructure investment in basic amenities can play in discouraging child labour and encouraging child schooling. Received: 24 August 1998/Accepted: 10 March 1999     

Of apes and men (including females!)

Two hundred seventy‐five undergraduate single women were surveyed to investigate whether a continuum of premarital sexual pressure exists. Participants were asked if they were pressured into 21 different sexual behaviors. For each behavior, they responded to forced‐choice questions about the stage of dating at which the pressure occurred and the type of pressure most often experienced. Over 50% of the participants reported being pressured into kissing, breast and genital manipulation, and oral contact with their partners' genitals. Further, participants were likely to be pressured into kissing and some forms of fondling while casually dating; and masturbation, oral genital contact, and intercourse while seriously dating. Guttman analysis supports the existence of a four‐step continuum of sexual pressure from persistent physical attempts, to positive statements, to threats of force, to the use of force.     

Innovation as the source of long term economic growth

This paper concerns some economic aspects of innovation particularly as the source of long term growth. Economic history supplies many examples of the rejuvenation of economies which, at various points in time, could legitimately have been considered ‘ageing’. The author asks ‘Could Britain's turn come now?’     

Managerial manpower planning— A systematic approach

At what ages should managers be recruited? Are the young managers receiving the right sort of experience at an early stage in their careers? What effect will the proposed merger have on the career prospects in the company.....? Questions such as these are likely to face every company from time to time, but finding the answers can be very difficult. The task may be made much easier through the application of some simple analytical techniques. These techniques are discussed here in the form of a case study.