Discover the most talked about and latest scientific content & concepts.

Concept: Official statistics


The application of Preventive Maintenance (PM) and Statistical Process Control (SPC) are important practices to achieve high product quality, small frequency of failures, and cost reduction in a production process. However there are some points that have not been explored in depth about its joint application. First, most SPC is performed with the X-bar control chart which does not fully consider the variability of the production process. Second, many studies of design of control charts consider just the economic aspect while statistical restrictions must be considered to achieve charts with low probabilities of false detection of failures. Third, the effect of PM on processes with different failure probability distributions has not been studied. Hence, this paper covers these points, presenting the Economic Statistical Design (ESD) of joint X-bar-S control charts with a cost model that integrates PM with general failure distribution. Experiments showed statistically significant reductions in costs when PM is performed on processes with high failure rates and reductions in the sampling frequency of units for testing under SPC.

Concepts: Official statistics, Probability, Process capability, Process management, Quality, Statistical process control, Statistical significance, Statistics


While the majority of veteran suicides involve firearms, no contemporary data describing firearm ownership among US veterans are available. This study uses survey data to describe the prevalence of firearm ownership among a nationally representative sample of veterans, as well as veterans' reasons for firearm ownership.

Concepts: Official statistics, Opinion poll, Sampling


In surveillance of subterranean fauna, especially in the case of rare or elusive aquatic species, traditional techniques used for epigean species are often not feasible. We developed a non-invasive survey method based on environmental DNA (eDNA) to detect the presence of the red-listed cave-dwelling amphibian, Proteus anguinus, in the caves of the Dinaric Karst. We tested the method in fifteen caves in Croatia, from which the species was previously recorded or expected to occur. We successfully confirmed the presence of P. anguinus from ten caves and detected the species for the first time in five others. Using a hierarchical occupancy model we compared the availability and detection probability of eDNA of two water sampling methods, filtration and precipitation. The statistical analysis showed that both availability and detection probability depended on the method and estimates for both probabilities were higher using filter samples than for precipitation samples. Combining reliable field and laboratory methods with robust statistical modeling will give the best estimates of species occurrence.

Concepts: Croatia, Official statistics, Survey sampling, Probability, Statistics, Applied mathematics, Probability theory, Slovenia


Purpose . We aimed to understand how employer characteristics relate to the use of incentives to promote participation in wellness programs and to explore the relationship between incentive type and participation rates. Design . A cross-sectional analysis of nationally representative survey data combined with an administrative business database was employed. Settings/Subjects . Random sampling of U.S. companies within strata based on industry and number of employees was used to determine a final sample of 3000 companies. Of these, 19% returned completed surveys. Measures . The survey asked about employee participation rate, incentive type, and gender composition of employees. Incentive types included any incentives, high-value rewards, and rewards plus penalties. Analysis . Logistic regressions of incentive type on employer characteristics were used to determine what types of employers are more likely to offer which type of incentives. A generalized linear model of participation rate was used to determine the relationship between incentive type and participation. Results . Employers located in the Northeast were 5 to 10 times more likely to offer incentives. Employers with a large number of employees, particularly female employees, were up to 1.25 times more likely to use penalties. Penalty and high-value incentives were associated with participation rates of 68% and 52%, respectively. Conclusion . Industry or regional characteristics are likely determinants of incentive use for wellness programs. Penalties appear to be effective, but attention should be paid to what types of employees they affect.

Concepts: Type, Incentive, Opinion poll, Official statistics, Regression analysis, Logistic regression, Sampling, Employment


Household survey data are collected by governments, international organizations, and companies to prioritize policies and allocate billions of dollars. Surveys are typically selected from recent census data; however, census data are often outdated or inaccurate. This paper describes how gridded population data might instead be used as a sample frame, and introduces the R GridSample algorithm for selecting primary sampling units (PSU) for complex household surveys with gridded population data. With a gridded population dataset and geographic boundary of the study area, GridSample allows a two-step process to sample “seed” cells with probability proportionate to estimated population size, then “grows” PSUs until a minimum population is achieved in each PSU. The algorithm permits stratification and oversampling of urban or rural areas. The approximately uniform size and shape of grid cells allows for spatial oversampling, not possible in typical surveys, possibly improving small area estimates with survey results.

Concepts: Opinion poll, Official statistics, Sample, Demography, Rural area, Population, Sampling, Statistics


Secondary analyses of survey data collected from large probability samples of persons or establishments further scientific progress in many fields. The complex design features of these samples improve data collection efficiency, but also require analysts to account for these features when conducting analysis. Unfortunately, many secondary analysts from fields outside of statistics, biostatistics, and survey methodology do not have adequate training in this area, and as a result may apply incorrect statistical methods when analyzing these survey data sets. This in turn could lead to the publication of incorrect inferences based on the survey data that effectively negate the resources dedicated to these surveys. In this article, we build on the results of a preliminary meta-analysis of 100 peer-reviewed journal articles presenting analyses of data from a variety of national health surveys, which suggested that analytic errors may be extremely prevalent in these types of investigations. We first perform a meta-analysis of a stratified random sample of 145 additional research products analyzing survey data from the Scientists and Engineers Statistical Data System (SESTAT), which describes features of the U.S. Science and Engineering workforce, and examine trends in the prevalence of analytic error across the decades used to stratify the sample. We once again find that analytic errors appear to be quite prevalent in these studies. Next, we present several example analyses of real SESTAT data, and demonstrate that a failure to perform these analyses correctly can result in substantially biased estimates with standard errors that do not adequately reflect complex sample design features. Collectively, the results of this investigation suggest that reviewers of this type of research need to pay much closer attention to the analytic methods employed by researchers attempting to publish or present secondary analyses of survey data.

Concepts: Official statistics, Baseball statistics, Regression analysis, Social research, Sampling, Epidemiology, Statistics, Scientific method


Four-sided, non-climbable pool fencing is an effective strategy for preventing children from drowning in home swimming pools. In 2009, the Queensland Government introduced legislation to improve the effectiveness of pool fencing. This study explores community attitudes towards the effectiveness of these legislative changes and examines child (<5 years) drowning deaths in pools. Data from the 2011 Queensland Computer-Assisted Telephone Interviewing (CATI) Social Survey include results from questions related to pool ownership and pool fencing legislation. Fatal child drowning cases between 1 January 2005 and 31 December 2015 were sourced from coronial data. Of the 1263 respondents, 26/100 households had a pool. A total of 58% believed tightening legislation would be effective in reducing child drowning deaths. Pool owners were more likely to doubt the effectiveness of legislation (p < 0.001) when compared to non-pool owners. Perceptions of effectiveness did not differ by presence of children under the age of five. There were 46 children who drowned in Queensland home pools (7.8/100,000 pools with children residing in the residence/annum) between 2005 and 2015. While pool owners were less likely to think that tightening the legislation would be effective, the number of children drowning in home swimming pools declined over the study period. Drowning prevention agencies have more work to do to ensure that the most vulnerable (young children in houses with swimming pools) are protected.

Concepts: Automated computer telephone interviewing, Computer-assisted personal interviewing, Official statistics, Human swimming, Pool fence, Computer-assisted telephone interviewing, Drowning, Swimming pool


Colorectal cancer (CRC) is the second leading cause of cancer-associated mortality in the USA. The faecal microbiome may provide non-invasive biomarkers of CRC and indicate transition in the adenoma-carcinoma sequence. Re-analysing raw sequence and metadata from several studies uniformly, we sought to identify a composite and generalisable microbial marker for CRC.

Concepts: Official statistics, Colorectal cancer


While it is estimated that 15% of couples worldwide are infertile, this figure hinges critically on the quality, inclusiveness and availability of infertility data sources. Current infertility data and statistics fail to account for the infertility experiences of some social groups. We identify these people as the invisible infertile , and refer to their omission from infertility data and statistics-whether intentional or unintentional-as the process of invisibilization . We identify two processes through which invisibilization in survey data is produced: sampling, with focus on exclusionary definitions of the population at-risk, and survey instrument design, with focus on skip patterns and question wording. Illustrative examples of these processes are drawn from the Integrated Fertility Survey Series and the Demographic and Health Surveys. Empirical research is not designed in an objective vacuum. Rather, survey instruments and sampling techniques are shaped and influenced by the sociocultural norms and geopolitical context of the time and place in which they are created and conducted, reflecting broader social beliefs about family building and reproduction. Furthermore, population policy singularly aimed at curbing overpopulation in high fertility parts of the world limits the type of reproduction data collected, effectively rendering the infertility of some groups epidemiologically unfathomable. In light of these sociocultural and geopolitical forces, many marginalized groups are missing from reproductive health (RH) statistics. The omission of entire groups from the scientific discourse casts doubt on the quality of research questions, validity of the analytic tools, and accuracy of scientific findings. Invisibility may also misguide evidence-based RH and family planning policies and deter equitable access to reproductive healthcare for some social groups, perpetuating social inequalities.

Concepts: Infertility, Population, Official statistics, Opinion poll, Sampling, Family planning, Fertility, Demography


Web-based self-report surveying has increased in popularity, as it can rapidly yield large samples at a low cost. Despite this increase in popularity, in the area of youth mental health, there is a distinct lack of research comparing the results of Web-based self-report surveys with the more traditional and widely accepted computer-assisted telephone interviewing (CATI).

Concepts: Automated computer telephone interviewing, Computer-assisted personal interviewing, Official statistics, Computer-assisted telephone interviewing