Differences In Sample Composition Research Articles

Dropout in a Longitudinal Survey of Amazon Mechanical Turk Workers With Low Back Pain: Observational Study.

Surveys of internet panels such as Amazon's Mechanical Turk (MTurk) are common in health research. Nonresponse in longitudinal studies can limit inferences about change over time. This study aimed to (1) describe the patterns of survey responses and nonresponse among MTurk members with back pain, (2) identify factors associated with survey response over time, (3) assess the impact of nonresponse on sample characteristics, and (4) assess how well inverse probability weighting can account for differences in sample composition. We surveyed adult MTurk workers who identified as having back pain. We report participation trends over 3 survey waves and use stepwise logistic regression to identify factors related to survey participation in successive waves. A total of 1678 adults participated in wave 1. Of those, 983 (59%) participated in wave 2 and 703 (42%) in wave 3. Participants who did not drop out took less time to complete previous surveys (30 min vs 35 min in wave 1, P<.001; 24 min vs 26 min in wave 2, P=.02) and reported having fewer health conditions (5.88 vs 6.6, P<.001). In multivariate models predicting responding at wave 2, lower odds of participation were associated with more time to complete the baseline survey (odds ratio [OR] 0.98, 95% CI 0.97-0.99), being Hispanic (compared with non-Hispanic, OR 0.69, 95% CI 0.49-0.96), having a bachelor's degree as their terminal degree (compared with all other levels of education, OR 0.58, 95% CI 0.46-0.73), having more pain interference and intensity (OR 0.75, 95% CI 0.64-0.89), and having more health conditions. In contrast, older respondents (older than 45 years age compared with 18-24 years age) were more likely to respond to the wave 2 survey (OR 2.63 and 3.79, respectively) and those whose marital status was divorced (OR 1.81) and separated (OR 1.77) were also more likely to respond to the wave 2 survey. Weighted analysis showed slight differences in sample demographics and conditions and larger differences in pain assessments, particularly for those who responded to wave 2. Longitudinal studies on MTurk have large, differential dropouts between waves. This study provided information about the individuals more likely to drop out over time, which can help researchers prepare for future surveys.

Are Large-Scale Test Scores Comparable for At-Home Versus Test Center Testing?

The COVID-19 pandemic led to a proliferation of remote-proctored (or "at-home") assessments. The lack of standardized setting, device, or in-person proctor during at-home testing makes it markedly distinct from testing at a test center. Comparability studies of at-home and test center scores are important in understanding whether these distinctions impact test scores. This study found no significant differences in at-home versus test center test scores on a large-scale admissions test using either a randomized controlled trial or an observational study after adjusting for differences in sample composition along baseline characteristics.

Sample, time, and wording effects on estimating the prevalence of childfree adults: Insights from Japan.

Childfree adults neither have nor want children, but estimates of their prevalence vary widely, leading to ambiguity about how common this family status actually is. The goal of this study is to examine the effects of sample composition, time, and question wording on estimates of the prevalence of childfree adults. We pool 83 nationally representative estimates of the prevalence of childfree adults in Japan since 2000 using meta-regression to identify the influence of sex, marital status, year, and survey question. Prevalence estimates are higher when computed from samples of women than men, from samples of singles than married people, from samples collected more recently, and from surveys asking questions about expectations than wants. Most of the variation in estimates of the prevalence of childfree adults can be attributed to differences in sample composition, time, and question wording. Taking these factors into account, we estimate that over 2.5 million Japanese adults age 18-50, or 5.64% of this population, were childfree in 2020.

Analysing mixed-mode effects of computer assisted telephone and personal interviews: A case study based on survey data from the international social survey programme module on environment

Due to Covid-19 restrictions, surveys often could not be conducted in originally planned face-to-face mode, and switched to online modes or used different mixed-mode designs. A combination of CATI and CAPI was used for the Austrian ISSP survey on Environment 2020/2021 (N=1.261), which in the past had always been conducted face-to-face. Mixed-mode surveys facilitate field access in pandemic times and show potential to reduce non-response and coverage errors (desired selection effect). However, the combination of different modes comes along with a series of risks such as mode-effects causing bias due to measurement effects. From an analytical perspective, the challenge arising is to disentangle selection and measurement effects. Thus, we analyse differences in the factorial structure and response distributions of two social constructs using Bayesian multigroup confirmatory factor analysis and linear regression. These represent institutional trust and the willingness to sacrifice for environmental protection. The findings show support for scalar invariance and therefore the absence of CAPI vs. CATI mode-effects on the factorial structure for both constructs. However, despite adjusting for differences in sample composition we observe a higher average willingness within the CATI sample. Based on these results, we discuss implications for the interpretation of mode effects in mixed mode surveys.

Concurrent, Web-First, or Web-Only? How Different Mode Sequences Perform in Recruiting Participants for a Self-Administered Mixed-mode Panel Study

Abstract During the COVID-19 pandemic, many survey programs switched to self-administered modes of data collection, often offering respondents both web-based and paper-based questionnaires. However, there is little guidance as to when to offer which mode, especially when the aim is to recruit participants for a panel survey. This study examines the effectiveness of different mode-sequence designs by analyzing an experiment implemented in the recruitment wave of the German panel study “Family Research and Demographic Analysis.” We randomly assigned 108,256 individuals aged 18–49 years to one of three mode-sequence-design conditions: concurrent, web-first including a paper-based questionnaire with the second reminder (web-first-2), and web-first including a paper-based questionnaire with the third reminder (web-first-3). A fourth, simulated group did not receive a paper-based questionnaire (web-only). We analyzed how different mode-sequence designs affected outcome rates, sample composition, response distributions, data quality, share of paper-based questionnaires, postage costs, number of postal mailings in the recruitment wave, and participation in the first regular wave. Our results show no differences in response distributions and small differences in sample composition across the four mode-sequence designs. As the web-first-2 and simulated web-only designs yielded comparatively good response and recruitment rates at reasonable costs, we recommend their use when surveying adults between 18 and 49 years old.

Effects of freeze-thaw intensities on N2O release from subsurface wastewater infiltration system

Subsurface wastewater infiltration system (SWIS) is a low-investment and cost-effective wastewater treatment technology. Nitrous oxide (N2O), an important greenhouse and ozone-depleting gas, is a major by-product of biological denitrification processes within SWIS. Although SWIS has been widely applied in varying zones, until now, whether and how periodical freeze-thaw cycles (FTCs) occurring in aerobic layers affect N2O release still remain unclear? In this study, two runs were arranged, which covered two freeze-thaw (FT) intensities of − 5 °C/5 °C and − 15 °C/5 °C, respectively. An in-situ simulation system of SWIS was carried out to monitor N2O release and microbial community structure in different profiles. The result revealed that raising FT intensity decreased the rate of nitrogen removal of SWIS. Average removal rate of TN under strong FTCs was 88.65–88.97%, which was 1.32–2.47% lower than that under weak FTCs conditions. In addition, a positive correlation was found between FT numbers and N2O release. The contribution of anaerobic zone increased from 29.24% to 75.16% with extending the FT cycles from 1 to 9. High-throughput sequencing results showed that different FT intensities had distinct effects on microbial communities. Euryarchaeota abundance increased significantly under strong FT treatment, while Proteobacteria abundance sharply decreased from 49.5% to 7.6% at day 27 of stable operation. PCA analysis shows that bacterial community composition of samples treated with weak FT and CK is similar. While significant differences in sample composition were found between strong and weak FT treatments, which was the main reason resulting in different N2O release patterns.

Differences in demographics and behaviors across two web-based survey platforms: Observations from a study of risk perceptions of heated tobacco products (HTPs)

With an escalating popularity of online surveys in behavioral research,it is critical to understand how different sources of participants can yield differing outcomes. While Mturk has been used for online surveys for almost two decades, a recent introduction of online panels allows researchers to choose participants fromvariety of pools. This study aims to contribute toexisting knowledge of how participants from different online platforms differ in their characteristics and behavioral responses which might affect the outcomes. 300 participants were recruited each from Mturk and Prime panels for a 20 mins long survey assessing perceptions and intentions to use Heated tobacco products (HTPs). Participants answered demographic and tobacco-use related questions includingtheir vaccination and masking for COVID-19. They were shown a picture and description of a recently launched HTP. Further, participants answered questions about their awareness of HTPs, risk perception of health conditions from use of different tobacco products (cigarettes, e-cigarettes and HTPs) and perceived severity of COVID-19 infection in smokers, vapers and HTP users. Results showed significant differences in Mturk and Prime panel participants’ demographics and tobacco-use. Prime panels showed more racially diverse population (chi-sq = 10.07, p < 0.02) and significantly more current smokers (chi-sq = 44.74, p < 0.01) and current e-cigarette users (chi-sq = 38.04, p < 0.01) compared with Mturk. Mean perception scores for COVID risk in tobacco users were significantly different between Prime panels and Mturk. Study highlights significant differences in sample composition and responses that might be helpful in choosing one online platform over another based on specific study requirements.

Validation of the Finnish Version of the Unified Dyskinesia Rating Scale

Introduction: The Unified Dyskinesia Rating Scale (UDysRS) was developed to provide a comprehensive rating tool of dyskinesia in Parkinson’s disease (PD). Because dyskinesia therapy trials involve multicenter studies, having a scale that is validated in multiple non-English languages is pivotal to international efforts to treat dyskinesia. The aim of the present study was to organize and perform an independent validation of the UDysRS Finnish version. Methods: The UDysRS was translated into Finnish and then back-translated into English using 2 independent teams. Cognitive pretesting was conducted on the Finnish version and required modifications to the structure or wording of the translation. The final Finnish version was administered to 250 PD patients whose native language is Finnish. The data were analyzed to assess the confirmatory factor structure to the Spanish UDysRS (the reference standard). Secondary analyses included an exploratory factor analysis (EFA), independent of the reference standard. Results: The comparative fit index (CFI), in comparison with the reference standard factor structure, was 0.963 for Finnish. In the EFA, where variability from sample to sample is expected, isolated item differences of factor structure were found between the Finnish and Reference Standard versions of the UDysRS. These subtle differences may relate to differences in sample composition or variations in disease status. Conclusion: The overall factor structure of the Finnish version was consistent with that of the reference standard, and it can be designated as the official version of the UDysRS for Finnish speaking populations.

Beyond question wording: How survey design and administration shape estimates of disability

BackgroundBetween 2008 and 2014, annual estimates of disability prevalence among U.S. adults varied somewhat across federal surveys that use a standardized measure of disability, but trends over-time were relatively stable and consistent. In 2014, however, estimates of disability from the Survey of Income and Program Participation (SIPP) increased markedly relative to previous years and were much higher than disability estimates from other federal surveys. ObjectiveTo examine why disability prevalence among adults aged 40 and older substantially increased in the first wave of the 2014 SIPP Panel. MethodsWe consider three factors that may have contributed to the rise in disability: data processing, context effects linked to question order, and sampling. To do so, we compare estimates with and without survey weights and imputed data, analyze supplemental disability-related data collected among SIPP participants, and employ decomposition analysis to assess what proportion of the increase in disability can be attributed to changes in sample composition. ResultsWe find evidence that differences in sample composition contributed to the observed rise in disability prevalence in SIPP between 2011 and 2014. There is less evidence that weighting and imputation or context effects played a role. ConclusionsPrevious studies emphasize differences in operationalization and conceptualization of disability as the major factor driving discrepancies in disability estimates. This study suggests that other factors related to survey design and administration may influence disability measurement. Such aspects of surveys, like question order and sampling, may be difficult to standardize, leading to meaningful cross-survey differences in disability estimates.

Employment Among People With Spinal Cord Injury in 22 Countries Across the World: Results From the International Spinal Cord Injury Community Survey

ObjectivesTo describe the employment situation of individuals with spinal cord injury (SCI) in 22 countries participating in the International Spinal Cord Injury community survey, to compare observed and predicted employment rates, to estimate gaps in employment rates among people with SCI compared with the general population, and to study differences in employment between men and women. DesignCross-sectional survey. SettingCommunity. ParticipantsPeople of employable age (N=9875; 18-64 y) with traumatic or non-traumatic SCI (including cauda equina syndrome) who were at least 18 years of age at the time of the survey, living in the community, and able to respond to one of the available language versions of the questionnaire. InterventionsNot applicable Main Outcome MeasuresThe observed employment rate was defined as performing paid work for at least 1 hour a week, and predicted employment rate was adjusted for sample composition from mixed logistic regression analysis. ResultsA total of 9875 participants were included (165-1174 per country). Considerable differences in sample composition were found. The observed worldwide employment rate was 38%. A wide variation was found across countries, ranging from 10.3% to 61.4%. Some countries showed substantially higher or lower employment rates than predicted based on the composition of their sample. Gaps between the observed employment rates among participants with SCI and the general population ranged from 14.8% to 54.8%. On average, employment rates were slightly higher among men compared with women, but with large variation across countries. Employment gaps, however, were smaller among women for most countries. ConclusionsThis first worldwide survey among people with SCI shows an average employment rate of 38%. Differences between observed and predicted employment rates across countries point at country-specific factors that warrant further investigation. Gaps with employment rates in the general population were considerable and call for actions for more inclusive labor market policies in most of the countries investigated.

Detection of Amyloid Beta (Aβ) Oligomeric Composition Using Matrix-Assisted Laser Desorption Ionization Mass Spectrometry (MALDI MS).

The use of MALDI MS as a fast and direct method to detect the Aβ oligomers of different masses is examined in this paper. Experimental results suggest that Aβ oligomers are ionized and detected as singly charged ions, and thus, the resulting mass spectrum directly reports the oligomer size distribution. Validation experiments were performed to verify the MS data against artifacts. Mass spectra collected from modified Aβ peptides with different propensities for aggregation were compared. Generally, the relative intensities of multimers were higher from samples where oligomerization was expected to be more favorable, and vice versa. MALDI MS was also able to detect the differences in oligomeric composition before and after the incubation/oligomerization step. Such differences in sample composition were also independently confirmed with an in vitro Aβ toxicity study on primary rat cortical neurons. An additional validation was accomplished through removal of oligomers from the sample using molecular weight cutoff filters; the resulting MS data correctly reflected the removal at the expected cutoff points. The results collectively validated the ability of MALDI MS to assess the monomeric/multimeric composition of Aβ samples. Graphical Abstract ᅟ.

Facial affect processing in incarcerated violent males: A systematic review

Abstract Previous reviews exploring facial affect processing among forensic samples have focused on the presence of psychopathy and/or have not distinguished on the basis of offence type. In order to develop understandings about etiological processes implicated in different types of antisocial behavior, the principle aim of this review was to systematically explore facial affect processing in incarcerated violent offenders, relative to other non-violent offenders, sexual offenders, and non-offenders. Following a systematic search of electronic databases and subsequent manual search, eight studies were assessed as meeting inclusion criteria, of which seven obtained a quality score deemed acceptable for review. These studies examined recognition accuracy, sensitivity and response bias for seven emotion categories (including neutral) in incarcerated male offenders with a history of violence. Findings supported the presence of generally impaired facial affect processing among violent offenders, including deficits in fear, anger, and disgust. Overall the findings of the review did not support the presence of a hostile attribution bias among violent offenders. The review also highlights differences in sample composition, stimuli, and study designs in emotion recognition research. Recommendations are made for future work on facial affect processing in clinically relevant groups.

A self-reference problem in test score normalization

It is considered standard practice to transform IRT-scaled test scores into standard normal variables for regression analysis in order to enable comparison with other research whose test scores are similarly transformed. This paper calls this practice into question. I show that these transformations can potentially result in radically different estimates of regression parameters due to differences in sample composition. Regression coefficient comparisons between different samples that use z-standardized test scores is only possible if the samples are considered to be random draws from the same population. I outline several different methods to deal with this problem and the caveats attached to each.

Gender Differences in Unemployment Dynamics and Initial Wages Over the Business Cycle

Using administrative data from Spanish Social Security for the period 2002-2013, we explore differences between unemployed men and women in their probabilities to find a job, their initial wages if they find a new job, and the likelihood to fall back into unemployment. We estimate bivariate proportional hazard models for unemployment duration and for the consecutive job duration for men and women separately, and decompose the gender gap using a non-linear Oaxaca decomposition. Gender differentials in labour market outcomes are procyclical, probably due to the procyclical nature of typically male occupations. While a higher level of education protects women in particular from unemployment, having children hampers women’s employment and initial wages after unemployment. There are lower gender gaps in the public sector and in high technology- firms. Decompositions show that the gender gaps are not explained by differences in sample composition. Indeed, if women had similar characteristics to men, the gender gap would be even wider.

Gender Differences in Unemployment Dynamics and Initial Wages over the Business Cycle

Using administrative data from Spanish Social Security for the period 2002–2013, we explore differences between unemployed men and women in: their probabilities to find a job, their initial wages if they find a new job, and the likelihood to fall back into unemployment. We estimate bivariate proportional hazard models for unemployment duration and for the consecutive job duration for men and women separately, and decompose the gender gap using a non-linear Oaxaca decomposition. Gender differentials in labour market outcomes are procyclical, probably due to the procyclical nature of typically male occupations. While a higher level of education protects women in particular from unemployment, having children hampers women’s employment and initial wages after unemployment. There are lower gender gaps in the public sector and in high technology- firms. Decompositions show that the gender gaps are not explained by differences in sample composition. Indeed, if women had similar characteristics to men, the gender gap would be even wider.

A Multisite Benchmarking Trial of Capnometry Guided Respiratory Intervention for Panic Disorder in Naturalistic Treatment Settings

Panic disorder (PD) is associated with hyperventilation. The efficacy of a brief respiratory feedback program for PD has been established. The aim of the present study was to expand these results by testing a similar program with more clinically representative patients and settings. Sixty-nine adults with PD received 4 weeks of Capnometry Guided Respiratory Intervention (CGRI) using Freespira, which provides feedback of end-tidal CO2 (PETCO2) and respiration rate (RR), in four non-academic clinical settings. This intervention is delivered via home use following initial training by a clinician and provides remote monitoring of client adherence and progress by the clinician. Outcomes were assessed post-treatment and at 2- and 12-month follow-up. CGRI was associated with an intent-to-treat response rate of 83% and a remission rate of 54%, and large decreases in panic severity. Similar decreases were found in functional impairment and in global illness severity. Gains were largely sustained at follow-up. PETCO2 moved from the slightly hypocapnic range to the normocapnic range. Benchmarking analyses against a previously-published controlled trial showed very similar outcomes, despite substantial differences in sample composition and treatment settings. The present study confirms prior clinical results and lends further support to the viability of CGRI in the treatment of PD.

The Mediterranean Plastic Soup: synthetic polymers in Mediterranean surface waters.

The Mediterranean Sea has been recently proposed as one of the most impacted regions of the world with regards to microplastics, however the polymeric composition of these floating particles is still largely unknown. Here we present the results of a large-scale survey of neustonic micro- and meso-plastics floating in Mediterranean waters, providing the first extensive characterization of their chemical identity as well as detailed information on their abundance and geographical distribution. All particles >700 μm collected in our samples were identified through FT-IR analysis (n = 4050 particles), shedding for the first time light on the polymeric diversity of this emerging pollutant. Sixteen different classes of synthetic materials were identified. Low-density polymers such as polyethylene and polypropylene were the most abundant compounds, followed by polyamides, plastic-based paints, polyvinyl chloride, polystyrene and polyvinyl alcohol. Less frequent polymers included polyethylene terephthalate, polyisoprene, poly(vinyl stearate), ethylene-vinyl acetate, polyepoxide, paraffin wax and polycaprolactone, a biodegradable polyester reported for the first time floating in off-shore waters. Geographical differences in sample composition were also observed, demonstrating sub-basin scale heterogeneity in plastics distribution and likely reflecting a complex interplay between pollution sources, sinks and residence times of different polymers at sea.

Re-evaluation of Pleistocene and Holocene long bone robusticity trends with regards to age-at-death estimates and size standardization procedures

Long-term trends in robusticity of lower limb bones in the genus Homo through the Pleistocene until the present have been proposed, which have been interpreted as a consequence of decreasing levels of mobility and activity patterns, changes in lifestyle, and environmental factors. There has also long been evidence that skeletal strength increases over an individual's lifespan. This increase is caused by continuous bone remodeling that optimizes the structure of a bone to resist mechanical loadings and creates a balance between endosteal resorption and subperiosteal apposition. However, none of the previous studies of temporal trends in robusticity has considered both processes and analyzed how individual age-related robusticity might influence higher-level temporal trends. This paper therefore explores temporal trends in robusticity of lower limb long bones within the genus Homo and considers how individual ages-at-death can confound published evolutionary trends, given the fact that some aspects of relative bone strength tend to increase over individual lifespans. Cross-sectional diaphyseal properties of the midshaft and proximal femur and midshaft tibia of Pleistocene and early Holocene individuals, together with data on age-at-death are used to analyze changes in relative bone strength relative to individuals' ages and evolutionary time. The results show increasing bone strength in adulthood until the fourth decade and then a slight decrease, an observation that conforms to previously published results on recent human populations. However, no significant impact of age-at-death on the trends along an evolutionary trajectory has been detected. The evolutionary trends in femoral and tibial relative strength can be described as fluctuating, probably as a consequence of changing mobility patterns, environmentally and technologically influenced behaviors, and demographic processes. The differences between evolutionary trends published in several studies are explained primarily as a result of different ways of standardizing cross-sectional parameters for size, and differences in sample composition.

Effect of Storage Temperature on the Outgrowth and Toxin Production of Staphylococcus aureus in Freeze-Thawed Precooked Tuna Meat

The aim of this study was to determine the time for a 3-log CFU/g outgrowth of Staphylococcus aureus and its toxin production in previously frozen precooked tuna meat (albacore [Thunnus alalunga] prepared as loin, chunk, and flake or skipjack [Katsuwonus pelamis] prepared as chunk and flake) held either at 21 or 27°C. A five-strain cocktail of enterotoxin-producing S. aureus was surface inoculated with ∼10(3) CFU/g onto tuna samples. The experimental time-temperature conditions were designed to mimic common industry holding conditions. After a 3-h incubation at 37°C, inoculated samples were individually vacuum sealed and stored at 20°C for 4 weeks. Following frozen storage, samples were thawed to the target temperature (21 or 27°C) and then incubated aerobically. Growth of S. aureus in tuna was then monitored using Baird Parker agar; simultaneously, aerobic plate counts, enterotoxin production, and sensory profile (color and odor) were determined. The results showed that the time for a 3-log CFU/g increase was >20 h at 21°C and 8 to 12 h at 27°C for albacore, with toxin production observed at 14 to 16 h at 21°C and at 8 h at 27°C. A 3-log CFU/g increase for skipjack occurred at 22 to 24 h at 21°C and at 10 to 14 h at 27°C. The toxin production in skipjack started at 20 to 22 h at 21°C and at 8 to 10 h at 27°C. Toxin production was observed before a 3-log increase was achieved in albacore samples at 21°C. Under all conditions, toxins were detected when the cell density of S. aureus was 6 log CFU/g. Overall, significantly faster S. aureus growth was observed in albacore compared with skipjack (P < 0.05), possibly owing to differences in sample composition (e.g., pH and salt content). The data developed from this study can be used by the tuna industry to model the growth and enterotoxin production of S. aureus and to design manufacturing controls that ensure food safety.

A mixed mushroom control material to facilitate inter-laboratory harmonization of mushroom composition analyses

A wide range of nutrients and health-promoting non-nutrient components in mushrooms are a subject of international research, but specific reference materials to facilitate comparison of results among laboratories are lacking. Commercially available food matrix reference materials do not contain components unique to mushrooms (e.g., ergosterol, vitamin D2, chitin, beta-glucans, agaritine, ergothioneine). A mixed mushroom control material (CM) (homogeneous mixture of 15 types of mushrooms) was prepared and characterized for selected components, including proximates (moisture, protein, ash), total folate, folate vitamers, ergosterol, ergosterol metabolites, vitamin D2 (ergocalciferol), amino acids, total dietary fiber, agaritine, elements (sodium, potassium, phosphorous, magnesium, calcium, iron, copper, manganese, zinc), riboflavin, niacin, thiamin, vitamin B6, pantothenic acid. Subsamples of the CM are available to qualified laboratories from the Food Analysis Laboratory Control Center at Virginia Tech (Blacksburg, VA, USA), to be assayed concurrently with mushroom samples for which food composition data will be published along with results for the CM. Implementation of this CM should facilitate comparison of published data on mushroom composition and health benefit among species, and biodiversity within species by serving as common control sample that allows the separation of analytical variability from true differences in sample composition determined at different laboratories.