Pearls and pitfalls in the diagnosis of small oral biopsies.

Pathologic processes affecting the oral and maxillofacial region include a heterogenous group of diseases with widely variable biologic behaviors. Proper patient management begins with the establishment of an accurate diagnosis, which often relies on histopathologic interpretation of small tissue samples from oral lesions. While confident diagnosis of small oral biopsies can be challenging, an understanding of oral and maxillofacial disease and consistent clinicopathologic correlation can help pathologists recognize inflammatory confounders and overcome common errors in specimen management, including insufficient sample size and non-representative biopsy samples.

Errors in particle size and concentration analysis of pharmaceuticals.

Good particulate products require that particle segregation has been minimized. Moreover representative sampling is essential for adequate quality control of such products. This requires optimum design of procedures and equipment for both sampling and measurement. Representative test samples primarily require that all constituent particles have had equal chance of being taken from a lot of material, given their proportion. Moreover, a sufficient number of particles is necessary for good precision. This article discusses and exemplifies various potential errors during collection of small amounts from powder lots and during in-situ and on-line measurement, so that optimum consideration can be given to the design of adequate analytical procedures. It should be realized that the errors during sampling of particulate materials are very similar to those during collection of small portions for production of pharmaceutical tablets.

Compliance with Saliva Collection Protocol in Healthy Volunteers: Strategies for Managing Risk and Errors.

Salivary bioscience technologies such as electrophoresis are widely applied for diagnosing systemic health status. Diagnosis using a saliva sample has emerged as a preferred technique since the sample is easy to collect and the method is inexpensive and non-invasive. Salivary diagnostics have even been identified as potential substitutes for serum protein biomarkers. However, the optimal protocol for collecting saliva has not yet been established. In many scientific settings, such as randomized controlled trials, sampling and statistical errors often occur when handling samples from healthy volunteers. These errors can be due to the psychological behavior of the volunteers, subject nonadherence, questionnaire characteristics, collection methods, and/or sample processing. The purpose of the review presented here is to outline the strategies for managing the risk factors and to minimize the sampling errors during saliva collection in healthy volunteers.

Practical tips and common mistakes in ocular microbiology sampling and processing.

Ocular microbiology deals with miniscule samples from ocular infections, which are difficult to collect, process, and analyze, necessitating special skills, and the knowledge of troubleshooting errors to reach a specific diagnosis. In this article, we highlight several practical points in ocular microbiology, common mistakes, and various approaches to resolve them. We have covered sample collection from different ocular compartments, processing for smear preparation and culture, transport of samples, staining and reagents issues, artifacts and contaminants, and interpretation of in-vitro antimicrobial susceptibility testing reports. This review aims to help both ophthalmologists and microbiologists in making the practice of ocular microbiology and the interpretation of reports more reliable, hassle-free, and precise.

Sampling particulate matter for analysis - Controlling uncertainty and bias using the theory of sampling.

Sampling particulate matter for measuring the content of an analyte is a routine operation in many fields of engineering and science. However, sampling can lead to important bias and variance in concentration estimation because of sampling errors stemming from particulate matter heterogeneity. The goal of this study was to quantify bias, reproducibility and the degree of representativeness of a probabilistic sampling (PS) technique following principles from the Theory of sampling (TOS) and grab sampling (GS). PS was designed to control sampling errors, while GS did not exert any control over them. GS also included a step of sieve screening, which is common during sampling in some fields (e.g. soil sampling). Both techniques were used with two different analytes, namely steel microspheres and copper sulfate, at two different concentrations, in order to assess sampling errors and sampling performance. The sampling method had the most significant effect on sampling bias and relative variance, and therefore, on the degree of sampling representativeness. The most important result is the demonstration that probabilistic sampling improves the degree of representativeness of concentrations measurements by more than two orders of magnitudes by significantly decreasing bias and relative variance. The lot containing the physical analyte lead to larger bias and relative variance compared to the lot containing the chemical analyte. GS resulted in largely biased results and a poor degree of representativeness. The results have also highlighted a significant problem associated with the screening of larger particles as performed in GS. This alteration of the primary sample decreased the variability of the resulting concentration measurements, but it also biased them significantly.

Sampling of particulate materials with significant spatial heterogeneity - Theoretical modification of grouping and segregation factors involved with correct sampling errors: Fundamental Sampling Error and Grouping and Segregation Error.

There has been an extensive abuse of Gy's Formula during the entire history of applied TOS (Theory of Sampling), it being applied too liberally to almost any aggregate material conceivable for many material classes of extremely different compositions with significant (to large, or extreme) fragment size distribution heterogeneity, for example many types of municipal and industrial waste materials. This abuse regimen is for the most part characterized by lack of fundamental TOS competence and the historical context of Gy's formula. The present paper addresses important theoretical details of TOS, which become important as sampling rates increase at the conclusion of the full 'lot-to-analysis sampling pathway regarding finer details behind TOS' central equations linking sampling conditions to material heterogeneity characteristics allowing the estimation of Total Sampling Error (TSE) manifestations. We derive a new, complementary understanding of the two conceptual factors, y the grouping factor and, z, the segregation factor, intended to represent the local (increment scale) and long-range (increment to lot-scale) heterogeneity aspects of lot materials, respectively. We contrast the standard TOS exposé with the new formulation. While the phenomenological meaning and content of the new proposed factors (y and z) remains the same, their numerical values and bracketing limits are different with z now representing more realistic effects of liberation and segregation combined. This new formulation makes it easier to get a first comprehensive grasp of TOS' dealings with sampling of significantly heterogeneous materials. We believe this may present a slightly easier path into the core issues in TOS when sampling and sub-sampling gets closer to the final aliquot scale.

Estimating access to drinking water and sanitation: The need to account for uncertainty in trend analysis.

Nationally representative household surveys are the main source of data for tracking drinking water, sanitation and hygiene (WASH) coverage. However, all survey point estimates have a certain degree of error that must be considered when interpreting survey results for policy and decision making. In this article, we develop an approach to characterize and quantify uncertainty around WASH estimates. We apply it to four countries - Bolivia, Gambia, Morocco and India - representing different regions, number of data points available and types of trajectories, in order to illustrate the importance of communicating uncertainty for temporal estimates, as well as taking into account both the compositional nature and non-linearity of JMP data. The approach is found to be versatile and particularly useful in the WASH sector, where the dissemination and analysis of standard errors lag behind. While it only considers the uncertainty arising from sampling, the proposed approach can help improve the interpretation of WASH data when evaluating trends in coverage and informing decision making.

An index of non-sampling error in area frame sampling based on remote sensing data.

Agricultural areas are often surveyed using area frame sampling. Using non-updated area sampling frame causes significant non-sampling errors when land cover and usage changes between updates. To address this problem, a novel method is proposed to estimate non-sampling errors in crop area statistics. Three parameters used in stratified sampling that are affected by land use changes were monitored using satellite remote sensing imagery: (1) the total number of sampling units; (2) the number of sampling units in each stratum; and (3) the mean value of selected sampling units in each stratum. A new index, called the non-sampling error by land use change index (NELUCI), was defined to estimate non-sampling errors. Using this method, the sizes of cropping areas in Bole, Xinjiang, China, were estimated with a coefficient of variation of 0.0237 and NELUCI of 0.0379. These are 0.0474 and 0.0994 lower, respectively, than errors calculated by traditional methods based on non-updated area sampling frame and selected sampling units.

Social network dynamics: the importance of distinguishing between heterogeneous and homogeneous changes.

Social network analysis is increasingly applied to understand the evolution of animal sociality. Identifying ecological and evolutionary drivers of complex social structures requires inferring how social networks change over time. In most observational studies, sampling errors may affect the apparent network structures.Here, we argue that existing approaches tend not to control sufficiently for some types of sampling errors when social networks change over time. Specifically, we argue that two different types of changes may occur in social networks, heterogeneous and homogeneous changes, and that understanding network dynamics requires distinguishing between these two different types of changes, which are not mutually exclusive. Heterogeneous changes occur if relationships change differentially, e.g. if some relationships are terminated but others remain intact. Homogeneous changes occur if all relationships are proportionally affected in the same way, e.g. if grooming rates decline similarly across all dyads. Homogeneous declines in the strength of relationships can strongly reduce the probability of observing weak relationships, producing the appearance of heterogeneous network changes. Using simulations, we confirm that failing to differentiate homogeneous and heterogeneous changes can potentially lead to false conclusions about network dynamics. We also show that bootstrap tests fail to distinguish between homogeneous and heterogeneous changes. As a solution to this problem we show that an appropriate randomization test can infer whether heterogeneous changes occurred. Finally, we illustrate the utility of using the randomization test by performing an example analysis using an empirical data set on wild baboons.

Why we know so little about prenatal care nationwide: an assessment of required methodology.

Policymakers, advocates, providers, recipients, and health services researchers all would agree that too little is known about the nature and effects of specific components of prenatal care. In the process of designing a national, longitudinal study of pregnancy and childbirth, we surfaced some methodological dilemmas that help to explain why so little is known. This article explores two of the major problems: (1) selecting a valid scientific sample of pregnant women and (2) collecting data from providers and women. From this analysis, seven methodological questions, which should be investigated through empirical field studies, are identified. Those field studies are essential if future research into the content of prenatal care is to achieve an acceptable level of methodological rigor.

Oral contraceptives and breast cancer: review of the epidemiologic literature.

Oral contraceptives have caused little or no overall increase in risk of breast cancer in women in developed countries, even in long-term users or after more than two decades since initial exposure. Limited evidence suggests a possible small increase in risk in users of oral contraceptives in developing countries, and further studies of breast cancer and oral contraceptives in low risk populations are warranted. Oral contraceptives may enhance risk of breast cancer in young women with a history of benign breast disease, and this possibility should also be investigated further. Multiple investigations have fairly consistently shown risk of breast cancer in women under age 45 years to be increased slightly in long-term users of oral contraceptives. Further studies should be conducted to elucidate the mechanism of this apparent phenomenon.

PIP: All reports of case-control and cohort studies of breast cancer and oral contraceptives (OC) were reviewed, estimated relative risks were summarized in 28 tables, and where possible, summary relative risks with 95% confidence limits and chi-square tests for heterogeneity were computed, for various categories of women. The categories were: case control and cohort, all ages combined; long-term users, case control, and cohort, all ages; 10-20 years after initial use, case control, and cohort, women of all ages; women in developing countries, case-control; by socioeconomic status; nulliparous; before 1st birth; by parity; by body mass index; with or without benign breast disease before or after diagnosis of benign breast disease; by duration of use before 1st pregnancy, case-control and cohort, after various latent period; before age 25, case-control; under age 45, case control, cohort, for long duration; by age at diagnosis; used OC near menopause; by type of formulation. OC use gave no increase in risk to women of all ages combined even after 2 decades of use. In low-risk populations, as in developing countries and in Seventh Day Adventists, OC use heightened risk about 21% but no particular risk factors stand out in detailed studies in developed countries. More work needs to be done to pinpoint the timing and type of benign lesion found to be associated with higher risk, only found in younger women. Similarly, more detailed studies with a pathology component should be done to find out what type of cells, ductal or lobular, and whether pre-existing tumors or new tumors, are involved in the inconsistent finding of increased risk in users under 25 before childbearing, and the more consistent heightened risk of 42% in users under 45 with long duration of use (10-20 years). So far there is no evidence of a screening bias. Further examination is also indicated of the possible higher risk for peri-menopausal women, and more data is needed on the relationship of medroxy-progesterone acetate to breast cancer.

Alternative dual system network estimators.

"When there are two or more data systems and none of them enumerates the population at an acceptable completeness level, concern about the bias due to underenumeration suggests an estimator which makes joint use of data compiled by the combined imperfect data systems. Conventional dual system estimators are based on the existence of two separate data collection systems. Dual system network estimators assume a main survey and a follow-up quality check survey. The main survey adopts a multiplicity counting rule that combines two mutually exclusive partial counting rules." Three dual system network estimators are presented. "One was previously proposed by Sirken (1979) and is the natural analogue of the conventional dual system estimator. The two other estimators are proposed as potential improvements, although neither of them is the natural analogue of the conventional dual system estimator. The design effects of the three estimators are compared analytically and empirically with one another, and with those of the single system conventional and network estimators." (summary in FRE)

An analysis of sampling errors for the Demographic Health Surveys.

"Sampling errors and design effects from 48 nationally representative surveys conducted under the Demographic and Health Surveys Program for a large number of variables concerning fertility, family planning, fertility intentions, child health and mortality etc. are analysed for the total sample, and for urban-rural domains, sub-national regions and various demographic and socio-economic subclasses.... At the country level, overall design effect (the ratio of actual to simple random sampling standard error) averaged over all variables and countries is around 1.5. Variation among countries is high, but less so than among variables. Urban-rural and regional differentials in design effects are small, and can be attributed to the fact that similar sample designs and cluster sizes were used across those domains within each country. Design effects for estimates over other subclasses are smaller, and tend towards 1.0 for small subclasses and differences, apart from the effect of sample weights which tends to persist undiminished across variables and subclasses." (SUMMARY IN FRE)

Social science stereotypes of the Mexican American woman: policy implications for research.

PIP: Reviewing the social science literature on the Chicana or Mexican American woman reveals a tenaciously perpetuated stereotype in which she appears almost exclusively as a submissive maternal figure. This may be related to an on-going trend to support studies of interpersonal or cultural characteristics of Chicanas and a resistance to undertake evaluations of systemic discrimination against Mexican American women. Almost all such studies investigated lower class samples, thus confounding ethnicity with socioeconomic status. The size and selection of many of the samples are questionable for purposes of generalizing to the entire population. Because many concepts are not defined in behavioral terms, they are seldom assessed empirically. The main concern is to what extent social scientists and the media are dictating norms to the Chicano family and to what extent are social planners and educators being influenced by these images. Examples from 3 distinct areas of research conclude with interpretations of Mexican American women that differ considerably from those with a heavy emphasis on cultural values: 1) demographic analyses of the 1970 Public Use Samples of the census that acknowledge the disadvantaged economic position of Mexican Americans; 2) studies that are beginning to measure empirically the family dynamics of Mexican Americans; and 3) family planning studies that attempt to examine the interaction between health care delivery systems and Mexican American contraceptive behavior. Trained and experienced Chicana researchers are needed to offset the male orientation and ethnocentrism that have characterized the social sciences.^ieng

Methodological problems and policy implications in Vietnamese refugee research.

PIP: This article is written with 2 objectives: 1) to describe some of the critical methodological problems encountered in research with Vietnamese refugees in San Diego, California, about whom few studies have been conducted previous to their arrival in 1975; and 2) to discuss the policy implications of research beset with these difficulties, some of which are unique to studies of refugee populations per se, while others are common to research on small ethnic minorities in general. This article focuses on 4 major issues: 1) the quality of refugee studies, 2) the purpose and functions of such research, 3) the ethical dilemmas of studying refugees, and 4) public policy implications of refugee research. Recommendations are offered to resolve some of these issues which would call for policy changes both in the ways that refugee research is conducted and in the training of researchers themselves.^ieng

[Up-to-dateness and accuracy of sampling statistics of the population and of the economically active population]. / Aktualitat und Genauigkeit der reprasentativen Statistik der Bevolkerung und des Erwerbslebens

PIP: The up-to-dateness and accuracy of the population and labor force statistics derived from the micro-census in the Federal Republic of Germany are assessed. The goals, development, and content of micro-censuses carried out between 1957 and 1982 are first reviewed. The next section deals with problems of up-to-dateness, including the speed with which results are produced and their thematic relevance. The remaining sections focus on problems of accuracy, with attention to the sampling plan, random errors, and systematic errors.^ieng

Appraisal of advanced sample tabulation of 1982 census of Shanghai.

PIP: This paper compares the 10% advanced sample tabulation of the 1982 census of Shangai with the aggregate data from the 1982 census. The sample's major population indicators have errors no greater than 5%, reliability is therefore above 95%. These indicators include urban population, population with a primary education and higher, employed population, married population, live births to women aged 15-64, population aged 0-14, population aged 15-64, and population aged 65 and over. The samle tabulation is generally reliable because the sample size is large and the random sampling method is reasonable. The sampling inferences of a few indicators are not reliable. The sex ratio in the sample shows an opposite trend from the sex ratio in the aggregate data, but this may be due to the uneven distribution of the collective households in the sample. Too large a proportion of collective households was sampled. The random sampling was not successful so far as the classifications of collective and domestic households is concerned. It may be a better idea to conduct separate samplings for collective and domestic households.^ieng

[Sampling problems in the population census of 1990]. / Az 1990. evi nepszamlalassal kapcsolatos mintavetelekrol.

PIP: The author reviews some methodological problems concerning the 1990 census of Hungary. Various sampling methods are discussed, and recommendations for improvements in sampling methods are proposed. (SUMMARY IN ENG AND RUS)^ieng

Post abortion syndrome?

PIP: There is general agreement that uncertainty persists regarding the psychological sequelae of abortion. Inconsistencies of interpretation stem from a lack of consensus about the symptoms, severity, and duration of mental disorder. In addition, opinions differ based on individual case studies and there is no national reporting system or adequate follow up system. Frequently, reviews combine studies conducted prior to and after the 1973 Supreme Court decision, mix elective abortion with those induced for medical reasons, or fail to distinguish between abortions performed early or late in gestation. The literature reveals methodological problems, a lack of controls, and sampling inadequacies. A review of the available literature and the files of "Abortion Research Notes" suggests that women at particular risk for postabortion stress reactions are those who terminate an originally wanted pregnancy, are strongly ambivalent, come very late in their pregnancy, or lack the support of significant others.^ieng

[The effect of sampling error on results of inverse projection: an empirical study]. / L'effetto dell'errore di campionamento sui risultati dell'inverse projection: uno studio empirico.

PIP: The authors conduct a simulation using population data from parishes in Perugia, Italy, from 1790 to 1830 to find out how sampling errors affect the results of inverse projections. They conclude that calculating the standard error is a necessary and possible part of such analyses.^ieng