Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “sampling design”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,747 records · Page 97Linked to original sources
PubMed2001

Pediatric residents' performance of ankle and knee examinations after an educational intervention.

BACKGROUND: Pediatric residents have the need for additional training in the care of common musculoskeletal injuries. OBJECTIVES: To implement and evaluate the effects of a teaching intervention on pediatric residents' knowledge and skills in performing the physical examination of the ankle and knee. STUDY DESIGN: Prospective, intervention, single-sample study design. METHODS: Pediatric residents (n = 58) on a 1-month adolescent medicine rotation received a teaching intervention after a baseline evaluation of their knowledge and skills. The teaching intervention was designed to improve their knowledge about and skills in performing physical examinations of the ankle and knee. The intervention included watching a videotape, followed by observation of the attending physician demonstrating the techniques on a standardized patient, followed by correct demonstration of the techniques by the resident. The residents' knowledge and skills were assessed at the end of the rotation and 9 months later. Knowledge was assessed using a written examination. Skills assessment was performed using a Clinical Skills Assessment Examination. RESULTS: At baseline, the residents performed 37% of the ankle and 18% of the knee physical examination techniques correctly. At 1 and 9 months, the residents' knowledge of ankle and knee examinations was greater than at baseline. The residents performed 77% of the techniques correctly at 1 month and 67% at 9 months. The residents performed 55% of the knee examination techniques correctly at 1 month and 47% at 9 months. The teaching intervention was rated highly by the residents. CONCLUSIONS: The residents' performance of ankle and knee examinations was suboptimal at baseline and improved significantly after the teaching intervention. Observed improvements persisted for a mean of 35 weeks. The teaching intervention described in this study could meet the need for improved ankle and knee examination skills, the 2 most common sites of skeletal injury in young athletes. The teaching model is novel in that it couples videotape and skills-based teaching methods with reliable evaluation methods. This model teaching method could be adapted for use in other pediatric residency training programs and other content areas. musculoskeletal, physical examination, resident curriculum.

Adolescent Medicine↗
PubMed2007

Problem solving and diabetes self-management: investigation in a large, multiracial sample.

OBJECTIVE: Problem solving is a core aspect of effective diabetes and chronic illness self-management, yet there are relatively few objective evaluations of problem-solving skills, especially in large, multiracial samples. RESEARCH DESIGN AND METHODS: A multiracial sample of 506 adults who have type 2 diabetes were assessed on a variety of patient characteristics, self-management behaviors, and biological and psychosocial measures. They also completed the Diabetes Problem-Solving Interview (DPSI). RESULTS: DPSI scores revealed significant variability across patients in problem-solving skill and were related to a number of comorbid conditions and complications but not to several other demographic factors, including race/ethnicity. Problem solving was also related to self-management behaviors (eating and exercise patterns), biological variables (A1C and lipids), and psychosocial measures (Diabetes Distress Scale) in multivariable analyses controlling for a variety of potential confounding factors. CONCLUSIONS: Diabetes problem solving, as measured by the DPSI, is an important patient skill related to several key diabetes management variables that appears applicable across racial and ethnic groups. Future research is needed to identify the generality versus specificity of diabetes problem solving and practical interventions to enhance problem-solving skills.

Aged↗
PubMedDate not supplied

Statistical approach for risk assessment of aflatoxin sampling plan used by manufacturers for raw shelled peanuts.

Processed food manufacturers often use acceptance sampling plans to screen out lots with unacceptable levels of contamination from incoming raw material streams. Sampling plan designs are determined by specifying sample sizes, sample preparation methods, analytical test methods, and accept/reject criteria. Sampling plan performance can be indicated by plotting acceptance probability versus contamination level as an operating characteristic (OC) curve. In practice, actual plan performance depends on the level of contamination in the incoming lot stream. This level can vary considerably over time, among different crop varieties, and among locales. To better gauge plan performance, a method of coupling an OC curve and crop distributions is proposed. The method provides a precise probabilistic statement about risk and can be easily performed with commercial spreadsheet software.

Aflatoxins↗
PubMed1993

The indirect patient care effect of a unit-based clinical nurse specialist on preventable pulmonary complications.

PURPOSE: To examine the indirect effect of a unit-based expert nurse on the incidence of preventable pulmonary complications, which were defined as malpositioned endotracheal tube and inadvertent extubation. DESIGN: A nonequivalent control group/separate samples pretest/posttest design was used to test differences in the incidence of preventable pulmonary complications before and after a 6-month intervention by a unit-based expert nurse in the experimental unit. Retrospective medical record audits were used to collect data on all consecutive admissions to the experimental and control units in March and April of years 1 and 2. RESULTS: Estimated risk ratios demonstrated a significant reduction in preventable pulmonary complications in the experimental unit after the test, even though the acuity was significantly higher in posttest patients. It was concluded that indirect patient care by a unit-based clinical nurse specialist can reduce the incidence of preventable pulmonary complications.

Adolescent↗
PubMed1995

Flow and image cytometric DNA measurements in fine needle aspiration samples of prostatic neoplasms.

OBJECTIVE: To compare the DNA content measured by flow cytometry (FCM) and image analysis (IA) from prostatic fine needle aspiration (FNA) samples. STUDY DESIGN: A total of 48 samples were studied. FCM was performed on propidium iodide-stained nuclei according to the Vindelov method, and image analysis was performed on Feulgen-stained slides. Positive FNA results were grade (1-3) and compared with Gleason grades. RESULTS: Aneuploidy was closely related to positive FNA results (P < .01). DNA histograms were found to be aneuploid in all grade 3 carcinomas (n = 13) by IA and in 11 cases (84.6%) by FCM. Grade 2 carcinomas (n = 9) were found to be aneuploid with both methods. In grade 1 carcinomas (n = 10), 2 cases exhibited IA aneuploid profiles, whereas all FCM cases were diploid. Aneuploid profiles were more often associated with high Gleason scores than were diploid ones (P < .01). Among the 16 patients with negative FNA results, two cases had tetraploid DNA profiles related to contaminating seminal vesicle cells. The difference in DNA measurements reached 10.4% but was not statistically significant. CONCLUSION: These findings show that the two methods, as applied to prostatic FNA samples, give comparable results and that seminal vesicle cells may be responsible for false tetraploid profiles.

Biopsy, Needle↗
PubMedDate not supplied

Reweighting DHS data to serve multiple perspectives.

Information about health and family planning infrastructures is collected through the service availability module (SAM), an important feature of the Demographic and Health Surveys (DHS) conducted in many developing countries. The DHS samples were designed to provide a representative sample of households and women of reproductive age. Using the weights routinely provided with DHS data sets, service accessibility can be described straightforwardly at the individual and household levels. However, without further adjustment, SAM data do not provide a representative picture of service delivery at the community, or primary sampling unit, level, where the data are collected. This report proposes a methodology for reweighting the SAM data, using rural data from the Egypt DHS as an illustration, so that available family planning facilities at this level may be usefully characterized at little additional cost.

Adolescent↗
PubMed2006

Sample size recalculation in internal pilot study designs: a review.

The adequacy of sample size is important to clinical trials. In the planning phase of a trial, however, the investigators are often quite uncertain about the sizes of parameters which are needed for sample size calculations. A solution to this problem is mid-course recalculation of the sample size during the ongoing trial. In internal pilot study designs, nuisance parameters are estimated on the basis of interim data and the sample size is adjusted accordingly. This review attempts to give an overview on the available methods. It is written not only for biometricians who are already familar with the the topic and wish to update their knowledge but also for users new to the subject.

Clinical Trials as Topic↗
PubMed1996

A basic framework of working environment control for occupational health in Japan.

This review deals with three aspects of occupational health practices in Japan, i.e., working environment control, work practice management and health care, with an emphasis upon working environment control. Control of chemical hazards and physical agents in working environment is of prime importance to prevent workers from health impairments due to the hazardous agents. The Japanese legislative system for control of hazardous agents in working environment is characterized by "workplace control", and it is different from "control of personal exposure based on exposure limits of hazardous substances". Hazardousness of working environment contaminated with a toxic substance is assessed by screening air sampling at workplace designated as Measurement A and by fixed point air sampling designated as Measurement B. Working environment was categorized as Control Class I, II or III with both geometric mean and geometric standard deviation of concentrations of the hazardous agent with reference to an "administrative control level". The nationwide survey of air concentrations of dust and lead at workplaces revealed that the present Japanese system of working environment control had been effective to reduce the number of the harmful workplaces evaluated as Control Class III, the worst category, in the decade of 1984-1993 throughout Japan.

Hazardous Substances↗
PubMed1990

Power and sample size calculations. A review and computer program.

Methods of sample size and power calculations are reviewed for the most common study designs. The sample size and power equations for these designs are shown to be special cases of two generic formulae for sample size and power calculations. A computer program is available that can be used for studies with dichotomous, continuous, or survival response measures. The alternative hypotheses of interest may be specified either in terms of differing response rates, means, or survival times, or in terms of relative risks or odds ratios. Studies with dichotomous or continuous outcomes may involve either a matched or independent study design. The program can determine the sample size needed to detect a specified alternative hypothesis with the required power, the power with which a specific alternative hypothesis can be detected with a given sample size, or the specific alternative hypotheses that can be detected with a given power and sample size. The program can generate help messages on request that facilitate the use of this software. It writes a log file of all calculated estimates and can produce an output file for plotting power curves. It is written in FORTRAN-77 and is in the public domain.

Case-Control Studies↗
PubMed2006

Disaster research methods: past progress and future directions.

Published results for 225 disaster studies were coded on methodological variables, severity of effects, and event year. Methods varied greatly, but cross-sectional, after-only designs, convenience sampling, and small samples were modal. Samples that were assessed before the disaster, selected for reasons of convenience, or were large tended to show less severe effects than other samples. Developing countries were underrepresented overall, but not in recent years. Certain desirable study characteristics (longitudinal designs, representative samples) have been decreasing in prevalence over time, whereas others (early first assessment) have been increasing. Innovations such as latent trajectory modeling or hierarchical linear modeling might advance the field's ability to capture the complexity of disasters, but the field still needs to attend to the fundamentals of sound epidemiologic research.

Data Interpretation, Statistical↗
PubMed2006

Effects of abdominal electroacupuncture on parameters related to obesity in obese women: a pilot study.

The aim of this study was to elucidate the effects of electroacupuncture at abdominal meridian points on various obesity-related parameters: body weight (BW), body fat (BF) percentage, body mass index (BMI), percent ideal body weight (PIBW), and waist (WC) and hip (HC) circumferences. All of these parameters changed significantly compared to pretreatment in this pilot uncontrolled study involving 31 women with obesity. The percent reductions were 5.3% in BW, 1.3% in BF, 4.7% in BMI, 6.0% in PIBW, 4.6% in WC, 6.2% in HC, and 2.1% in the WC/HC ratio. The most affected variable was WC (effect size=0.58). Since this was a pilot study with several limitations, such as a small sample size and absence of a control treatment and appropriate follow-up, further studies that include a randomized design, larger sample sizes, and more detailed data about the subjects are needed to convincingly show the effects of electroacupuncture at abdominal meridian points on overweight and obese patients.

Adipose Tissue↗
PubMed2001

Incidence of suicide ideation and attempts in adults: the 13-year follow-up of a community sample in Baltimore, Maryland.

BACKGROUND: Utilizing a prospectively designed community sample, we set out to estimate the rate of newly-incident suicidal ideation and attempts (non-fatal suicide behaviour) in a community sample, to evaluate antecedent sociodemographic characteristics and psychiatric disorders, and to assess use of mental health services in relation to non-fatal suicide behaviour. METHOD: Prospectively-gathered data was utilized from 3481 continuing participants in the 13-year follow-up of the Baltimore sample of the NIMH Epidemiologic Catchment Area survey interviewed in 1981, 1982 and 1993/6. RESULTS: The incidence of suicide attempts was estimated at 148.8 per 100,000 person-years and ideation at 419.9 per 100,000 person-years. Persons in the youngest age group, in the lowest socioeconomic status, and previously married persons were at increased risk for non-fatal suicide behaviour during the follow-up interval. Persons who reported suicidal ideation at baseline were more likely to report having attempted suicide at follow-up (RR = 6.09, 95% CI 2.58-14.36). Psychiatric disorders, especially depression and substance abuse, were associated with new-onset of non-fatal suicidal behaviour. While persons who reported newly-incident suicidal behaviour were more likely to report use of mental health services, few said that suicidal ideation or attempts were the reason for the visits. CONCLUSIONS: Suicidal ideation is a common and important antecedent to suicide attempts and deserves more attention in community and general medical settings.

Adolescent↗
PubMedDate not supplied

[Sampling plans in microbiological criteria for food and their "performance criteria"].

Statistically based acceptance sampling plans have been integrated into microbiological criteria for food in international trade for some time. Especially two- and three-class sampling plans for attributes are used, variables plans are applied less. A lot of examples can be found in the so-called ICMSF (International Commission on Microbiological Specifications for Foods) "sampling book" or in EU guidelines. However, quite often the required confidence and the assumptions on tolerable lot qualities on which the choice and design of sampling plans are based can't be deduced from such recommendations and prescriptions. These problems have led to critical discussion of the performance of two- and three-class sampling plans used in microbiological criteria, showing complex dependencies on microbiological limits and on the expected variability of sampling results. As a result means should be considered to use knowledge gained from process analyses in food production in the design of sampling plans. In this context the performance of acceptance sampling plans as prescribed in microbiological criteria for foods will be discussed as well as their role in recently developed food safety concepts.

Animals↗
PubMedDate not supplied

A psychometric assessment of the H & H Lactation scale in a sample of thai mothers using a repeated measurement design.

BACKGROUND: The H & H Lactation (H & H) scale is a useful instrument for understanding mothers' perceptions of insufficient milk supply, which is the common reason given for premature cessation of breastfeeding. This instrument may be used to intervene in postbirth dropoff in breastfeeding among mothers. OBJECTIVES: To examine construct and nomological validity and related psychometric evidence for the translated H & H scale using a repeated measurement design in a sample of Thai mothers. METHOD: A repeated measurement design with 196 mother-infant dyads. Data were collected at two time periods. At Time 1, data on the H & H and Index of Breastfeeding Status (IBS) scales were obtained between 36 and 48 hr postbirth. For Time 2, the same mothers completed the same instruments at 1 month postbirth. Psychometricproperties of the H & H scale were examined using convergent, discriminant, and nomological validity principles with instructural equation modeling. RESULTS: Based on judgment/classification task, exploratory/confirmatory factor analysis, and cross-validation using multisample analysis, only nine items of the H & H scale measured at Time 1 and Time 2 were found to be psychometrically sound for measuring insufficient milk supply for Thai mothers. An analysis of the influence of the nine-item of the H & H scale measured at Time 1 and Time 2 on the IBS measured at Time 2 showed that (a) the direct effects of two subscales of the H & H scale measured at Time 2 on the IBS were significant and positive, providing support for the nomological validity of the H & H scale; (b) each H& H factor at Time 1 had a significant influence on its corresponding factor at Time 2, supporting convergent validity; and (c) the crossover effects for each H & H factor for Time 1 and Time 2 data were nonsignificant, indicating discriminant validity. DISCUSSION: Overall, the 20-item H & H scale appears to be unreliable and invalid for measuring the concept of insufficient milk supply in cross-cultural studies. However, the short form of nine items is reliable and valid for Thai mothers. Further testing and development of the H & H scale and the proposed short form in other cultures and contexts is warranted.

Adult↗
PubMedDate not supplied

New statistical software for intralaboratory and interlaboratory quality control in clinical cytology. Validation in a simulation study on clinical samples.

OBJECTIVE: To design a statistical software package to provide automated calculations of normal and weighted and 3 indices. STUDY DESIGN: Prompted by the lack of commonly available software to compute weighted kappa and the nonproportionate workload needed to calculate our 3 variability indices manually, the new statistical software package was designed. To demonstrate the performance of the new CONQUISTADOR software, a simulation study (both intralaboratory and interlaboratory) was designed using 5,000 clinical samples randomly selected from a data file of > or = 200,000 conventional Pap smears and programmed to become "analyzed" by 12 cytologists in 5 imaginary laboratories. RESULTS: A representative set of both complete and partial outputs provided by the software, in Excel format (Microsoft, Redmond, Washington, U.S.A.) are shown to illustrate the different functions of the program. In the interlaboratory mode, the software calculates accuracy indicators (sensitivity, specificity, positive and negative predictive value, and their 95% CI), which are not common features of regular statistical packages; kappa and weighted kappa; and their 95% CI (comparison of single laboratories to all laboratories and pairwise comparisons between single laboratories). The 3 diagnostic variability indices can be computed separately for all samples or for only the positive samples. In the intralaboratory mode, the software calculates the same indices for individual cytologists. CONCLUSION: The CONQUISTADOR statistical package has properties that are useful in monitoring cytologic laboratory quality in both intralaboratory and interlaboratory settings. The software will be distributed by the National Institute of Health, Rome, for the delivery costs only.

Clinical Laboratory Techniques↗
PubMedDate not supplied

The odds of resilience.

This article presents sample research designs for the investigation of questions concerning resilience. Sample hypothesis from specific research designs are described in the form of odds ratios.

Adaptation, Psychological↗
PubMed1995

Strategies for sampling black and ethnic minority populations.

BACKGROUND: The objective of the study was to describe the design and sampling methods used to carry out face-to-face interviews with a sample of the black and ethnic minority population of the area. This study was conducted in the city of Bristol, England (part of Bristol and District Health Authority). METHODS: The sample was based on up to 1000 interviews with black Caribbean/African, South Asian and Far-East Asian residents. The design of the study focuses on the problems of definition of the appropriate group to sample and the various sampling techniques that were necessary to procure the interviews. RESULTS: A total of 574 interviews were carried out by bilingual interviewers matched for sex and ethnicity of the respondent, thereby allowing analysis that would be beneficial to the Health Authority in its planning and decision-making. CONCLUSIONS: The use of name spotting and 'snowball' sampling proved the most productive. The Electoral Register was preferred to the Family Health Services Authority lists. Interviewers must be carefully selected and adequately trained to work in this difficult area. The questionnaire must be culturally and linguistically acceptable across all the ethnic groups.

Africa↗