Managing data quality in a statistical agency

Includes bibliography

Propuesta para el establecimiento de un banco de datos estad��sticos = Proposal for the establishment of a statistical data bank

Incluye Bibliograf��a

Latin America and Caribbean experiences in electronic statistical data processing

Includes bibliography

The production of statistical data and information in the Caribbean: proposals for increasing efficiency in this sphere

Includes bibliography

Allelic frequencies and statistical data obtained from 12 codis STR loci in an admixed population of the Brazilian Amazon

The allelic frequencies of 12 short tandem repeat loci were obtained from a sample of 307 unrelated individuals living in Macap��, a city in the northern Amazon region, Brazil. These loci are the most commonly used in forensics and paternity testing. Based on the allele frequency obtained for the population of Macap��, we estimated an interethnic admixture for the three parental groups (European, Native American and African) of, respectively, 46%, 35% and 19%. Comparing these allele frequencies with those of other Brazilian populations and of the Iberian Peninsula population, no significant distances were observed. The interpopulation genetic distances (F_ST coefficients) to the present database ranged from F_ST = 0.0016 between Macap�� and Bel��m to F_ST = 0.0036 between Macap�� and the Iberian Peninsula.

Interactive Correlation Environment (ICE) - A Statistical Web Tool for Data Collinearity Analysis

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Statistical detection of spurious variations in daily raingauge data caused by changes in observation practices, as applied to records from various parts of the world

In the instrumental records of daily precipitation, we often encounter one or more periods in which values below some threshold were not registered. Such periods, besides lacking small values, also have a large number of dry days. Their cumulative distribution function is shifted to the right in relation to that for other portions of the record having more reliable observations. Such problems are examined in this work, based mostly on the two-sample Kolmogorov���Smirnov (KS) test, where the portion of the series with more number of dry days is compared with the portion with less number of dry days. Another relatively common problem in daily rainfall data is the prevalence of integers either throughout the period of record or in some part of it, likely resulting from truncation during data compilation prior to archiving or by coarse rounding of daily readings by observers. This problem is identified by simple calculation of the proportion of integers in the series, taking the expected proportion as 10%. The above two procedures were applied to the daily rainfall data sets from the European Climate Assessment (ECA), Southeast Asian Climate Assessment (SACA), and Brazilian Water Resources Agency (BRA). Taking the statistic D of the KS test >0.15 and the corresponding p-value <0.001 as the condition to classify a given series as suspicious, the proportions of the ECA, SACA, and BRA series falling into this category are, respectively, 34.5%, 54.3%, and 62.5%. With relation to coarse rounding problem, the proportions of series exceeding twice the 10% reference level are 3%, 60%, and 43% for the ECA, SACA, and BRA data sets, respectively. A simple way to visualize the two problems addressed here is by plotting the time series of daily rainfall for a limited range, for instance, 0���10���mm���day���1.

A Bayesian destructive weighted Poisson cure rate model and an application to a cutaneous melanoma data

In this article, we propose a new Bayesian flexible cure rate survival model, which generalises the stochastic model of Klebanov et al. [Klebanov LB, Rachev ST and Yakovlev AY. A stochastic-model of radiation carcinogenesis - latent time distributions and their properties. Math Biosci 1993; 113: 51-75], and has much in common with the destructive model formulated by Rodrigues et al. [Rodrigues J, de Castro M, Balakrishnan N and Cancho VG. Destructive weighted Poisson cure rate models. Technical Report, Universidade Federal de Sao Carlos, Sao Carlos-SP. Brazil, 2009 (accepted in Lifetime Data Analysis)]. In our approach, the accumulated number of lesions or altered cells follows a compound weighted Poisson distribution. This model is more flexible than the promotion time cure model in terms of dispersion. Moreover, it possesses an interesting and realistic interpretation of the biological mechanism of the occurrence of the event of interest as it includes a destructive process of tumour cells after an initial treatment or the capacity of an individual exposed to irradiation to repair altered cells that results in cancer induction. In other words, what is recorded is only the damaged portion of the original number of altered cells not eliminated by the treatment or repaired by the repair system of an individual. Markov Chain Monte Carlo (MCMC) methods are then used to develop Bayesian inference for the proposed model. Also, some discussions on the model selection and an illustration with a cutaneous melanoma data set analysed by Rodrigues et al. [Rodrigues J, de Castro M, Balakrishnan N and Cancho VG. Destructive weighted Poisson cure rate models. Technical Report, Universidade Federal de Sao Carlos, Sao Carlos-SP. Brazil, 2009 (accepted in Lifetime Data Analysis)] are presented.

New insights into methodology and interpretation of osteoarthritis. The study of Frassetto identified skeletal collection.

Osteoarthritis (OA) or degenerative joint disease (DJD) is a pathology which affects the synovial joints and characterised by a focal loss of articular cartilage and subsequent bony reaction of the subcondral and marginal bone. Its etiology is best explained by a multifactorial model including: age, sex, genetic and systemic factors, other predisposing diseases and functional stress. In this study the results of the investigation of a modern identified skeletal collection will be presented. In particular, we will focus on the relationship between the presence of OA at various joints. The joint modifications have been analysed using a new methodology that allows the scoring of different degrees of expression of the features considered. Materials and Methods The sample examined comes from the Sassari identified skeletal collection (part of ���Frassetto collections���). The individuals were born between 1828 and 1916 and died between 1918 and 1932. Information about sex and age is known for all the individuals. The occupation is known for 173 males and 125 females. Data concerning the occupation of the individuals indicate a preindustrial and rural society. OA has been diagnosed when eburnation (EB) or loss of morphology (LM) were present, or when at least two of the following: marginal lipping (ML), esostosis (EX) or erosion (ER), were present. For each articular surface affected a ���mean score��� was calculated, reflecting the ���severity��� of the alterations. A further ���score��� was calculated for each joint. In the analysis sexes and age classes were always kept separate. For the statistical analyses non parametric test were used. Results The results show there is an increase of OA with age in all the joints analyzed and in particular around 50 years and 60 years. The shoulder, the hip and the knee are the joints mainly affected with ageing while the ankle is the less affected; the correlation values confirm this result. The lesion which show the major correlation with age is the ML. In our sample males are more frequently and more severely affected by OA than females, particularly at the superior limbs, while hip and knee are similarly affected in the two sexes. Lateralization shows some positive results in particular in the right shoulder of males and in various articular surfaces especially of the superior limb of both males and females; articular surfaces and joints are quite always lateralized to the right. Occupational analyses did not show remarkable results probably because of the homogeneity of the sample; males although performing different activities are quite all employed in stressful works. No highest prevalence of knee and hip OA was found in farm-workers respect to the other males. Discussion and Conclusion In this work we propose a methodology to score the different features, necessary to diagnose OA, that allows the investigation of the severity of joint degeneration. This method is easier than the one proposed by Buikstra and Ubelaker (1994), but in the same time allows a quite detailed recording of the features. Epidemiological results can be interpreted quite simply and they are in accordance with other studies; more difficult is the interpretation of the occupational results because many questions concerning the activities performed by the individuals of the collection during their lifespan cannot be solved. Because of this, caution is suggested in the interpretation of bioarcheological specimens. With this work we hope to contribute to the discussion on the puzzling problem of the etiology of OA. The possibility of studying identified skeletons will add important data to the description of osseous features of OA, enriching the medical documentation, based on different criteria. Even if we are aware that the clinical diagnosis is different from the palaeopathological one we think our work will be useful in clarifying some epidemiological as well as pathological aspects of OA.

Does published orthodontic research account for clustering effects during statistical data analysis?

In orthodontics, multiple site observations within patients or multiple observations collected at consecutive time points are often encountered. Clustered designs require larger sample sizes compared to individual randomized trials and special statistical analyses that account for the fact that observations within clusters are correlated. It is the purpose of this study to assess to what degree clustering effects are considered during design and data analysis in the three major orthodontic journals. The contents of the most recent 24 issues of the American Journal of Orthodontics and Dentofacial Orthopedics (AJODO), Angle Orthodontist (AO), and European Journal of Orthodontics (EJO) from December 2010 backwards were hand searched. Articles with clustering effects and whether the authors accounted for clustering effects were identified. Additionally, information was collected on: involvement of a statistician, single or multicenter study, number of authors in the publication, geographical area, and statistical significance. From the 1584 articles, after exclusions, 1062 were assessed for clustering effects from which 250 (23.5 per cent) were considered to have clustering effects in the design (kappa = 0.92, 95 per cent CI: 0.67-0.99 for inter rater agreement). From the studies with clustering effects only, 63 (25.20 per cent) had indicated accounting for clustering effects. There was evidence that the studies published in the AO have higher odds of accounting for clustering effects [AO versus AJODO: odds ratio (OR) = 2.17, 95 per cent confidence interval (CI): 1.06-4.43, P = 0.03; EJO versus AJODO: OR = 1.90, 95 per cent CI: 0.84-4.24, non-significant; and EJO versus AO: OR = 1.15, 95 per cent CI: 0.57-2.33, non-significant). The results of this study indicate that only about a quarter of the studies with clustering effects account for this in statistical data analysis.

Semiparametric Normal Transformation Models for Spatially Correlated Survival Data

There is an emerging interest in modeling spatially correlated survival data in biomedical and epidemiological studies. In this paper, we propose a new class of semiparametric normal transformation models for right censored spatially correlated survival data. This class of models assumes that survival outcomes marginally follow a Cox proportional hazard model with unspecified baseline hazard, and their joint distribution is obtained by transforming survival outcomes to normal random variables, whose joint distribution is assumed to be multivariate normal with a spatial correlation structure. A key feature of the class of semiparametric normal transformation models is that it provides a rich class of spatial survival models where regression coefficients have population average interpretation and the spatial dependence of survival times is conveniently modeled using the transformed variables by flexible normal random fields. We study the relationship of the spatial correlation structure of the transformed normal variables and the dependence measures of the original survival times. Direct nonparametric maximum likelihood estimation in such models is practically prohibited due to the high dimensional intractable integration of the likelihood function and the infinite dimensional nuisance baseline hazard parameter. We hence develop a class of spatial semiparametric estimating equations, which conveniently estimate the population-level regression coefficients and the dependence parameters simultaneously. We study the asymptotic properties of the proposed estimators, and show that they are consistent and asymptotically normal. The proposed method is illustrated with an analysis of data from the East Boston Ashma Study and its performance is evaluated using simulations.