NFP update: researcher cites need to improve instruction

In the Philippines more and more couples are practicing natural family planning (NFP), but there is a need to improve instruction on this method to increase its effectiveness. Calendar rhythm has been the most popular technique of NFP, but failure rates have been high. This could be changed by improved calendar rythm instruction and the introduction of newer, more effective natural techniques like the basal body temperature, cervical mucus, and symptothermal methods. Dr. John E. Laing, in a paper entitled "research on Natural Family Planning in the Philippines," examines the trends in NFP and summarizes major findings of past research related to NFP and the status of current research. It also discusses the implications of such findings for the National Population Program and the needs for current research. Cting World Fertility Survey (WFS) data on 19 developing countries, Laing states that the Philippines is second only to Peru in current and past use of the rhythm method. He also indicates that since the start of the National Population Program in 1971, rhythm has been offered as an official program method. Yet, in the early years of the program rhythm was not promoted as actively as the other family planning methods. In the last few years, program, officials have become more interested in NFP. 1976 National Acceptor Survey (NAS) data showed that rhythm reduced fertility by 78% compared to the condom's 79%, oral contraceptive's 94%, and the IUD's 98%. A comparison of data from the 1972, 1974, and 1976 NAS indicated a decline in continuation rates and an increase in overall pregnancy rates for all methods except rhythm. The overall pregnancy rate of rhythm declined, but there was no significant change in continuation rate. Laing suggests that probably, while the national population program was increasingly recruiting less motivated couples to try other methods, the rhythm acceptors, who were largely self initiated, mantained earlier levels of motivaton. Evidence points to the widespread use of crude formulas that do not take into account individual variations in cycle length. Many users do not even fully understand the mechanism by which rhythm affects fertility. There is also little knowledge among acceptors of the new and more reliable techniques of NFP for identifying the safe and unsafe periods. Despite problems, a considerable number of acceptors still prefer rhythm to other methods. The commission on population has embarked on a solution to some of the problems by committing itself to the training of volunteers of community-based organizations, particlarly lay leaders. 3 large scale projects are planned for this purpose.     

What Comes After the Prestige Disaster? An Entropic Approach to Modeling the Recurrence of Major Oil Tanker Spills in Galicia

A methodology is presented to investigate the recurrence of extraordinary events. The approach is fully general and complies with a canon of inference establishing a set of basic rationality requirements scientific reasoning should satisfy. In particular, we apply it to model the interarrival time between disastrous oil spills in the Galician coast in the northwest of Spain, one of the greatest risk areas in the world, as confirmed by the Prestige accident of November 2002. We formulate the problem within the logical probability framework, using plausible logic languages with observations to allow the appropriate expression of evidences. Therein, inference is regarded as the joint selection of a pair of reference and inferred probability distributions, which better encode the knowledge about potential times between incidents provided by the available evidences and other higher-order information at hand. To solve it, we employ the REF relative entropy method with fractile constraints. Next, we analyze the variability of the joint entropic solution, as knowledge that a time has elapsed since the last recorded spill is added, by conditioning the evidences. Attention is paid to the variability of two representative parameters: the average reference recurrence time and an inferred characteristic probability fractile for the time to an event. In contrast with classical results, the salient consequence is their nonconstancy with the elapsed time and the appearance of a variability pattern indicating an observational memory, even under the assumption of one-parameter exponential models, traditionally regarded as memoryless. Tanker accidentality is therefore dynamic, changing as time goes on with no further accidents. Generality of the methodology entails that identical conclusions would apply to hazard modeling of any other kind of extraordinary phenomena. This should be considered in risk assessment and management.     

Getting the Goods on Social Capital1

Abstract This article presents an overview of the origins, development, rapid diffusion, and current usage of the concept of social capital in both the academic (research-oriented) and more applied (social policy) literature. Following a short quantitative survey of the appearance of the term in both theses and journals, various meanings of social capital are examined in the light of classical and contemporary sociological theory. Three main research approaches, which are based on the operationalization of social capital or its application as a heuristic device, are critically examined. These approaches are associated with the work ofJames Coleman, Pierre Bourdieu, and Robert Putnam, but there are also some references to the work of economists. The authors contend that, while social capital has value and appeal as a new term, basic theory needs greater development. In particular, attention should be paid to acknowledging the specific perspective on social capital that underlies its usage, the scale or level of analysis employed, and the value of a qualitative use of social capital.     

Influence of the sampling interval, decision limit and autocorrelation on the average run length in Cusum charts

This paper shows how the average run length for a one-sided Cusum chart varies as a function of the length of the sampling interval between consecutive observations, the decision limit for the Cusum statistic, and the amount of autocorrelation between successive observations. It is shown that the rate of false alarms can be decreased considerably, without modifying the rate of valid alarms, by decreasing the sampling interval and appropriately increasing the decision interval. It is also shown that this can be done even when the shorter sampling interval induces moderate autocorrelation between successive observations.     

Detecting possibly non-consecutive outliers in industrial time series

A method for robust estimation and multiple outlier detection in time series generated by autoregressive integrated moving average processes in industrial environments is developed. The procedure is based on reweighted maximum likelihood estimation using Huber or redescending weights and, therefore, generalizes the well-established robust M -estimation procedures used in the regression framework. When the scalar process is non-stationary, the computations required can be performed equally well using either rhe original undifferenced series or auxiliary differenced series. Whereas the latter alternative may be preferred for scalar series, the former might be extended to cope with vector partially non-stationary time series without differencing the series, thus avoiding non-invertibility and parameter identifiability problems caused by overdifferencing. The overall strategy is applied in two real industrial data sets.     

Cohort Changes in the Incidence of Care Need in West Germany Between 1986 and 2005

In Germany, the share of the older population has been continuously growing. Is the increase paralleled by a rising number of frail people, however? In search of an answer, we analyse the development of care need incidence in West Germany between 1986 and 2005 on the basis of longitudinal data from the German Socio-Economic Panel (SOEP). The results show a lower transition risk to care need for each successive cohort when all degrees of care need are taken into account. However, no change occurs when only severe care need is measured.     

Study of the quality of several asymptotic and near-exact approximations based on moments for the distribution of the Wilks Lambda statistic

In this paper a measure of proximity of distributions, when moments are known, is proposed. Based on cases where the exact distribution is known, evidence is given that the proposed measure is accurate to evaluate the proximity of quantiles (exact vs. approximated). The measure may be applied to compare asymptotic and near-exact approximations to distributions, in situations where although being known the exact moments, the exact distribution is not known or the expression for its probability density function is not known or too complicated to handle. In this paper the measure is applied to compare newly proposed asymptotic and near-exact approximations to the distribution of the Wilks Lambda statistic when both groups of variables have an odd number of variables. This measure is also applied to the study of several cases of telescopic near-exact approximations to the exact distribution of the Wilks Lambda statistic based on mixtures of generalized near-integer gamma distributions.     

Der Masterplan und sein Weg durch die Organisation

Organizations in the public sector, like the German police, are under increasing pressure to change in the face of new challenges. We discuss the complexity of change projects based on qualitative interviews with future top managers in the police. It emerges that employees do not faithfully implement top down change plans. Instead, they subject change plans to various adaptations based on their active sense-making which is influenced by cognitive and behavioral patterns of the organizational members. These micro processes of change severely restrict the plan-ability of change projects. Flexible and reflective procedures are required to successfully manage change, as plans are more often adapted as their champions ever intended.     

Efficient MCMC sampling in dynamic mixture models

We show how to improve the efficiency of Markov Chain Monte Carlo (MCMC) simulations in dynamic mixture models by block-sampling the discrete latent variables. Two algorithms are proposed: the first is a multi-move extension of the single-move Gibbs sampler devised by Gerlach, Carter and Kohn (in J. Am. Stat. Assoc. 95, 819–828, 2000); the second is an adaptive Metropolis-Hastings scheme that performs well even when the number of discrete states is large. Three empirical examples illustrate the gain in efficiency achieved. We also show that visual inspection of sample partial autocorrelations of the discrete latent variables helps anticipating whether blocking can be effective.