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Test-retest reliability is often estimated using naturally occurring data from test repeaters. In settings such as admissions testing, test takers choose if and when to retake an assessment. This self-selection can bias estimates of test-retest reliability because individuals who choose to retest are typically unrepresentative of the broader testing population and because differences among test takers in learning or practice effects may increase with time between test administrations. We develop a set of methods for estimating test-retest reliability from observational data that can mitigate these sources of bias, which include sample weighting, polynomial regression, and Bayesian model averaging. We demonstrate the value of using these methods for reducing bias and improving precision of estimated reliability using empirical and simulated data, both of which are based on more than 40,000 repeaters of a high-stakes English language proficiency test. Finally, these methods generalize to settings in which only a single, error-prone measurement is taken repeatedly over time and where self-selection and/or changes to the underlying construct may be at play. [ABSTRACT FROM AUTHOR]

Natural resources such as soil and water are essential to agriculture, especially in arid and semi-arid rain-fed areas, yet the impacts of managing these crucial natural resources on farm technical efficiency are little known. Using data from 400 households with 1031 plots, we examined the impacts of soil and water conservation measures (SWCMs) on the technical efficiency of farmers in the semi-arid Bundelkhand (central India). We estimated stochastic production frontiers, considering potential self-selection bias stemming from both observable and unobservable factors in the adoption of SWCMs at the farm level. The farm technical efficiency for adopters of SWCMs ranged from 0.68 to 0.72, and that for non-adopters ranged from 0.52 to 0.65, depending on how biases were controlled for. As the average efficiency is consistently higher for adopter farmers than the control group, promoting SWCMs could help to increase input use efficiency, especially in resource-deprived rain-fed systems in the semi-arid tropics. [ABSTRACT FROM AUTHOR]

Background Empirical evaluation of inverse probability weighting (IPW) for self-selection bias correction is inaccessible without the full source population. We aimed to: (i) investigate how self-selection biases frequency and association measures and (ii) assess self-selection bias correction using IPW in a cohort with register linkage. Methods The source population included 17 936 individuals invited to the Copenhagen Aging and Midlife Biobank during 2009–11 (ages 49–63 years). Participants counted 7185 (40.1%). Register data were obtained for every invited person from 7 years before invitation to the end of 2020. The association between education and mortality was estimated using Cox regression models among participants, IPW participants and the source population. Results Participants had higher socioeconomic position and fewer hospital contacts before baseline than the source population. Frequency measures of participants approached those of the source population after IPW. Compared with primary/lower secondary education, upper secondary, short tertiary, bachelor and master/doctoral were associated with reduced risk of death among participants (adjusted hazard ratio [95% CI]: 0.60 [0.46; 0.77], 0.68 [0.42; 1.11], 0.37 [0.25; 0.54], 0.28 [0.18; 0.46], respectively). IPW changed the estimates marginally (0.59 [0.45; 0.77], 0.57 [0.34; 0.93], 0.34 [0.23; 0.50], 0.24 [0.15; 0.39]) but not only towards those of the source population (0.57 [0.51; 0.64], 0.43 [0.32; 0.60], 0.38 [0.32; 0.47], 0.22 [0.16; 0.29]). Conclusions Frequency measures of study participants may not reflect the source population in the presence of self-selection, but the impact on association measures can be limited. IPW may be useful for (self-)selection bias correction, but the returned results can still reflect residual or other biases and random errors. [ABSTRACT FROM AUTHOR]

This article aims to compare the pattern of responses obtained by a web-based and a paper-based survey used to investigate the transit safety of travellers in railway stations in Sweden. This aim is achieved by evaluating whether the response and the completion rates change as the surveys progress, assessing the effect of the survey mode on respondents' answers (after controlling for the surveys' internal consistency and differences in the samples), and the potential impact of the order of alternatives in multiple-choice questions on the responses. To carry out the study, a sample of 500 responses was taken from each population and later compared using a series of statistical tests. Findings indicate that despite the surveys' high internal consistency, the prevalence of victimisation, fear of crime, and precautions detected in the web survey was higher than those found in the paper survey. The web survey shows a major drop just after the initial questions, while the paper survey shows a more stable pattern of responses, but was also affected by a single compulsory question that pushed the completion rate down. Finally, the order of alternatives in multiple-choice questions (fixed or random) did not affect the answers given by the respondents, providing a solid base for safety interventions in transit environments, regardless of survey mode. The article concludes by making suggestions for both research and practice. [ABSTRACT FROM AUTHOR]

The dissemination of conservation agriculture (CA) technologies has become the objective of a growing number of projects aimed at reducing food insecurity in vulnerable areas of the world. While many studies have found that CA increases farm productivity, little is known about the components of the productivity gains related to CA adoption. CA is a knowledge‐intensive technology, and it is expected to affect both technical efficiency (TE) and input productivity positively. Using cross‐sectional farm‐level data of 220 maize farmers in Bangladesh, we measure the impact of CA on farmers' TE. We first apply propensity score matching (PSM) to create comparable counterfactual groups of CA and non‐CA farmers. Then, we use a stochastic frontier with correction for self‐selection bias to analyse TE. Finally, we fit a stochastic meta‐frontier (SMF) model to the data and use it to compare TE across the two farmer groups. The analysis showed that CA farmers exhibit greater TE levels than non‐CA farmers. This can be attributed to enhancements in farm management, leading to 8% and 9% increases in their productivity and TE, respectively. Thus, there is a case for policymakers to strengthen programs delivering CA technologies that improve food security in Bangladesh. [ABSTRACT FROM AUTHOR]

Declining survey response rates have increased the costs of travel survey recruitment. Recruiting respondents based on their expressed willingness to participate in future surveys, obtained from a preceding survey, is a potential solution but may exacerbate sample biases. In this study, we analyze the self-selection biases of survey respondents recruited from the 2017 U.S. National Household Travel Survey (NHTS), who had agreed to be contacted again for follow-up surveys. We apply a probit with sample selection (PSS) model to analyze (1) respondents' willingness to participate in a follow-up survey (the selection model) and (2) their actual response behavior once contacted (the outcome model). Results verify the existence of self-selection biases, which are related to survey burden, sociodemographic characteristics, travel behavior, and item non-response to sensitive variables. We find that age, homeownership, and medical conditions have opposing effects on respondents' willingness to participate and their actual survey participation. The PSS model is then validated using a hold-out sample and applied to the NHTS samples from various geographic regions to predict follow-up survey participation. Effect size indicators for differences between predicted and actual (population) distributions of select sociodemographic and travel-related variables suggest that the resulting samples may be most biased along age and education dimensions. Further, we summarized six model performance measures based on the PSS model structure. Overall, this study provides insight into self-selection biases in respondents recruited from preceding travel surveys. Model results can help researchers better understand and address such biases, while the nuanced application of various model measures lays a foundation for appropriate comparison across sample selection models. [ABSTRACT FROM AUTHOR]

Simple Summary: Studies looking at the reduction of breast cancer deaths from screenings that are not randomized may suffer bias because of "self selection". This occurs when even before screening takes place, people who choose to be screened are already at lower risk of dying than those who do not participate. A publication by Dibden et al. applied a correction to remove the effect of self-selection. There is concern, though, that because the correction was developed using data from a group of women in Sweden, where the healthcare system and people's attitudes and behavior may not be the same, it may not be suitable when applied to studies on women in other countries such as Canada. In fact, the authors of the Canadian study checked for and found no evidence of self-selection bias. Observational studies of cancer screening are subject to bias associated with the self-selection of screening participants for whom the underlying probability of cancer death may be different from those who do not participate. Dibden et al. reviewed data on mortality reduction from 27 observational studies of mammography screening expressed in terms of relative risk for women who were screened versus not screened. Results were given, both unadjusted and after application of a correction for self-selection. The correction was based on a constant (1.17)—the ratio of risks of death in screening non-attenders versus those not invited, derived from a Swedish study. For some of the studies this correction had a large effect in diminishing the measured mortality benefit associated with screening. In particular, application to The Pan-Canadian Study of Mammography Screening, a study whose authors had previously tested for and found no evidence of self-selection bias, caused the estimated benefit to decrease from 40% to 10%. The appropriateness of applying a correction based on a constant to a population whose healthcare environment and screening participation rates are very different from those from which it was derived is questionable. [ABSTRACT FROM AUTHOR]

Camping is a recreational activity that links people with their physical surroundings and the environment. Hence, efforts in promoting camping activities may help promote sustainable and accessible recreation and tourism. This research focuses on preferences and barriers for camping in Israel as perceived by frequent, occasional, and noncampers. The findings of an online study with 665 respondents show that focusing only on current campers may create self-selection bias and overlook the barriers that prevent people from camping. While noncampers shared some barriers with campers, they also experienced more barriers regarding information gaps (location of campsites) and camping equipment. All participants had a similar preference for solitude and lack of crowding. These findings create a dilemma for camping managers and marketing campaigns: to reduce the barriers that prevent low frequency campers and noncampers from camping or to keep the situation as is and minimize overcrowding in campsites. [ABSTRACT FROM AUTHOR]

We examine a potential self‐selection bias in different samples of experimental subjects depending on the payment scheme offered in the recruiting process. We ran four field experiments in which undergraduate students in a microeconomics course were invited to voluntarily set their own goal for the final exam. They were informed that they would be given a monetary reward (else nothing) if their actual grade were higher than or equal to their goal. Rewards were an increasing (quadratic) function of the goal. We aimed at studying whether subjects' willingness to participate in the experiment depends on their expected performance under different advertised reward criteria, like a rank‐order tournament and piece‐rate pay. Given that judgments about future performance are closely tied to previous performance, the midterm exam scores from the current academic course are compared between participants and nonparticipants in order to analyze sample‐sorting effects. We find that when a rank‐order tournament is offered alone or in combination with another reward mechanism, high‐performing students are more likely than low‐performing ones to participate in the experiment. [ABSTRACT FROM AUTHOR]

Copyright of Contaduría y Administración is the property of Facultad de Contaduria y Administracion-Universidad Nacional Autonoma de Mexico and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

While most previous studies in the Western context have found a positive correlation between volunteering and health, this positive relation is not conclusive since the self-selection bias inherent in this question has not been addressed well. Meanwhile, this relation has been rarely explored in non-Western countries, especially mainland China, where institutionalized volunteer practices are more emergent. Using a nationally representative sample (N = 4967) from the 2013 Survey on Philanthropic Behaviors of Urban Citizens in China, this study followed the counterfactual framework under quasi-experimental design and adopted two treatment effects models - propensity score matching and nearest neighbor matching - to detect the net effect of volunteering on individuals' self-rated health. Analyses from both matching models consistently indicate that after conditioning on the covariates, volunteers on average, have a higher self-rated health score than non-volunteers. The results also provide evidence of upward bias about the positive effect of volunteering on health in models that use standard multiple regression approach. In sum, the findings demonstrate that volunteering is a real benefit for health, but the positive effect is likely to be overestimated when self-selection bias is not accounted for. Finally, this study presents new evidence that the positive effect of volunteering is consistent across national boundaries to the Chinese context. [ABSTRACT FROM AUTHOR]

Beef quality assurance initiatives have been developed to assure consumers of the quality and safety of supplied beef, as well as the environmental‐orientation of farm production practices. However, the potential economic benefits of quality schemes to European beef cattle farmers have been overlooked. This paper uses farm‐level data to identify the drivers of Irish farmers' participation in Bord Bia's Beef and Lamb Quality Assurance Scheme (BLQAS) in 2012, and assesses the impact of participation on farm gross margins. After controlling for potential self‐selection bias, we cannot find reliable evidence that the gross margins of participants in beef quality assurance schemes have been affected by their decision to participate. Consequently, lack of financial incentives can be a barrier to farmer participation in beef quality assurance schemes [EconLit citations: L25, M21, Q12]. [ABSTRACT FROM AUTHOR]

Many researchers have identified the issue of self-selection bias hindering the ability to detect nutrient effects in healthy populations. However, it appears that no effort has been made to mitigate this potential design flaw. By recruiting individuals on the basis of pre-trial dietary intake, the Memory and Attention Supplementation Trial aimed to capture a cohort of participants with a wide variety of dietary intake, thus increasing the likelihood of a diverse range of nutrient status. This perspective specifically examines the profile of these trial volunteers and in doing so, we present the first empirical evidence of self-selection bias when recruiting healthy volunteers for a randomized controlled trial of a nutrient-based supplement. These findings support the anecdotal proposal that traditional recruitment methods inherently attract trial volunteers who are vastly unrepresentative of the population and threatens the generalizability of this field of research. Alternative approaches to recruitment, including a-priori screening for baseline diet quality and nutrient status, are discussed as essential design recommendations to ensure accurate interpretation of nutrient effects within the context of baseline participant characteristics.

Background: Participation bias in exercise studies is poorly understood among older adults. This study was aimed at looking into whether older persons who volunteer to participate in an exercise study differ from nonvolunteers. Methods: A self-reported questionnaire on physical activity and general health was mailed out to 1000 persons, aged 60 or over, who were covered by the medical insurance of the French National Education System. Among them, 535 answered it and sent it back. Two hundred and thirty-three persons (age 69.7 ±7.6, 65.7% women) said they would volunteer to participate in an exercise study and 270 (age 71.7 ±8.8, 62.2% women) did not. Results: Volunteers were younger and more educated than nonvolunteers, but they did not differ in sex. They had less physical function decline and higher volumes of physical activity than nonvolunteers. Compared with volunteers, nonvolunteers had a worse self-reported health and suffered more frequently from chronic pain. Multiple logistic regressions showed that good self-reported health, absence of chronic pain, and lower levels of physical function decline were associated with volunteering to participate in an exercise study. Conclusions: Volunteers were fitter and healthier than nonvolunteers. Therefore, caution must be taken when generalizing the results of exercise intervention studies. [ABSTRACT FROM AUTHOR]

Previous research suggests that participation in victim–offender mediation (VOM) can lower the risk of reoffending. However, no randomized controlled trials have been done to examine this effect of VOM. Given that participation in VOM is voluntary, previous studies likely suffer from self-selection bias. To address this bias, we compared reoffending rates of three different offender groups: offenders who participated in VOM; offenders who were willing to participate, but whose counterpart declined VOM; and offenders unwilling to participate (total N = 1,275). Results replicated that participation in VOM predicts lower reoffending rates and suggested that this effect is not solely due to a self-selection bias. Suggestions are made for future research to examine why VOM causes lower reoffending rates. [ABSTRACT FROM AUTHOR]

Copyright of Japanese Sociological Review / Shakaigaku Hyoron is the property of Japan Sociological Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

User-generated hotel ratings have been found to be an important element in customers' decision making. Nevertheless, most hotel ratings online show average ratings that are extremely positive. Thus, the question is raised of whether online ratings reflect objective evaluation of the reviewers. This study examines the distribution of online ratings and compares it the distribution of offline ratings. Online hotel score ratings reported on Booking.com were extracted and compared with offline rating scores from a field survey. Online and offline hotel ratings of eight hotels located in Seoul were collected. The ratings were compared using Welch's t-test. Overall, both online and offline ratings for all eight hotels show generally positive distribution curves. The distribution curves exhibit shapes analogous to those considered to contain self-selection bias. The randomized offline ratings did not produce more moderate ratings as predicted. Thus, no indication of non-response bias was found. Practically, this study supports the notion that hotels listed on online travel agencies such as Booking.com may already have passed certain quality criteria, thereby providing competitive marketplaces for customers searching for hotels online. [ABSTRACT FROM AUTHOR]

The journal Scientometrics recently featured a study on the citation impact of video abstracts and subsequent debate on the actual scope of the same impact. As things stand, the crucial issue of that debate lies in the motivations behind the authors' choice to equip (some of) their articles with video abstracts. It can be easily understood that those motivations are hardly observable, and it is indeed agreed that observational limitations make them difficult to unravel. Nonetheless, the debate has seen the emergence of two different positions. The first may be summarized as follows: ask the authors to speak out about their motivations and rely on the elicited answers. The second bases itself on the opposite cornerstone: let the data tell the story about authors' motivations. This recalls the distinction between stated preferences and revealed preferences. Here I develop some arguments in favor of the latter approach as far as the analysis of new media's citation impact is concerned. [ABSTRACT FROM AUTHOR]

Summary: The general health check is one of the most common preventive healthcare measures in many countries. In this study, we propose an empirical approach which jointly models the decision to obtain a general health check and healthcare utilization, tackling the self‐selection problem by using eligibility to obtain a health check for free as an instrumental variable. Eligibility has some exogenous variations by design and this helps us to partial out the effect of general health checks from self‐selection biases. We apply the model to a large 12‐year panel data set provided by the Korean National Health Insurance Service. We find that participation in the general health check increases healthcare utilization and ignored self‐selection generates substantial upward bias in the estimates. We also find that the health check effect shows noteworthy heterogeneity across gender and income groups. Before health checks, healthcare utilization of males and people in low income groups is lower than those of females and people in high income groups respectively. However, these become comparable across different groups after health checks. This finding implies that general health checks can be an effective vehicle for health equity. [ABSTRACT FROM AUTHOR]

The paper authored by Zong et al. (Scientometrics, 2019. 10.1007/s11192-019-03108-w) claims that equipping articles with a video abstract provides them a citation advantage. Here I argue that the study above does not consider two potential confounding factors, namely, the role played by self-citations as well as by the self-selection bias. Author self-citations push the citation premium of the articles analyzed in the study referenced above, thus the net effect of video abstracts is lower than expected. What is more, articles with a video abstract seem to associate with higher citations in comparison to their counterparts without the video companion due to the self-selection bias. Namely, authors may be prone to include a video abstract in the articles they believe are of outstanding quality and best representative of their research activities. All this suggests that the alleged citation advantage of video abstracts is, at least, of doubtful occurrence. [ABSTRACT FROM AUTHOR]

How does e-shopping impact household travel? To answer this question, which is particularly relevant for policymakers concerned with congestion, air pollution, and greenhouse gas emissions from transportation, we analyzed data from the 2017 National Household Travel Survey using propensity score matching. This allowed us to tackle the bias from households self-selecting into various levels of e-shopping and gain causal inference. Unlike other related papers in the literature, our unit of analysis is a household because travel and shopping decisions within a household are interrelated. We classified households into three groups based on how many orders per person per month they placed online: low (up to one), medium (more than once but less than four), and high (over four). We found that more e-shopping results in more household travel (number of trips, miles, and VMT), but this effect depends on e-shopping frequency and population density, and it affects weekdays more than weekends. E -shopping impacts household travel more for medium frequency e-shoppers in low density areas: compared to similar low frequency e-shoppers, on weekdays, they take on average 8 more monthly trips and travel ∼104 extra miles (including 31 miles for shopping). At the other end of the spectrum, high frequency e-shoppers in dense areas do not travel more on weekends than similar low e-shopping frequency households. To help reduce e-shopping induced travel, policymakers could encourage the creation of neighborhood depots where households would pick-up and return unwanted orders, and foster the development of virtual reality tools for shopping from home. • We analyze household travel data from the 2017 US National Household Travel Survey. • We use propensity score matching to infer causality between e-shopping and travel. • The impact on travel of e-shopping depends on its frequency and population density. • E-shopping increases household mileage most on weekdays and in low density areas. • There, mid-frequency e-shoppers travel ∼8 more weekday trips and 104 mi per month. [ABSTRACT FROM AUTHOR]

Background: Social media in scientific research offers a unique digital observatory of human behaviours and hence great opportunities to conduct research at large scale, answering complex sociodemographic questions. We focus on the identification and assessment of biases in social-media-administered surveys. Objective: This study aims to shed light on population, self-selection, and behavioural biases, empirically comparing the consistency between self-reported information collected traditionally versus social-media-administered questionnaires, including demographic and psychometric attributes. Methods: We engaged a demographically representative cohort of young adults in Italy (approximately 4,000 participants) in taking a traditionally administered online survey and then, after one year, we invited them to use our ad hoc Facebook application (988 accepted) where they filled in part of the initial survey. We assess the statistically significant differences indicating population, self-selection, and behavioural biases due to the different context in which the questionnaire is administered. Results: Our findings suggest that surveys administered on Facebook do not exhibit major biases with respect to traditionally administered surveys in terms of neither demographics nor personality traits. Loyalty, authority, and social binding values were higher in the Facebook platform, probably due to the platform's intrinsic social character. Conclusions: We conclude that Facebook apps are valid research tools for administering demographic and psychometric surveys, provided that the entailed biases are taken into consideration. Contribution: We contribute to the characterisation of Facebook apps as a valid scientific tool to administer demographic and psychometric surveys, and to the assessment of population, self-selection, and behavioural biases in the collected data.

Online reviews suffer from self-selection biases. One of these is under-reporting bias: those who have an extreme experience, either positive or negative, are more likely to review a product than those who have a moderate experience, and consequently are overrepresented in the sample of reviews. In this paper we study whether under-reporting bias decreases the effectiveness of the mean star-rating as a criterion for choosing between competing products of different but unobservable qualities. We formulate a model of consumer choice and the decision to review, and simulate this model in a variety of scenarios. We find that if under-reporting bias decreases the effectiveness of the mean star-rating, this is usually only for products that are of either extremely poor or extremely good quality. Even in these cases, the effectiveness is reduced only when the extent of bias is extreme and the variance in quality is low. Otherwise, the presence of under-reporting bias generally does not decrease, and in fact, often enhances the effectiveness of the mean star-rating as a measure of relative quality. [ABSTRACT FROM AUTHOR]

A large number of microfinance impact assessment studies were conducted in different parts of the world in last two decades, but most of the impact assessment methods were put to questions. There were methodological concerns associated with both external validation and internal validation. Many microfinance impact assessment studies have suffered from issues related to counterfactual selection, project/programme placement bias and self-selection bias. To address those problems, this paper studied some of the important impact assessment frameworks. This study involved extensive literature scanning. Important impact assessment models were analysed and discussed focusing on unit of analysis, selection of impact variables, selection of comparison group and control of self-selection bias and project placement bias. The study concluded that a methodical analysis of counterfactual would help in avoiding self-selection bias and project placement bias. [ABSTRACT FROM AUTHOR]

The overarching goal of nutrition labelling is to transform intrinsic credence attributes into searchable cues, which would enable consumers to make informed food choices at lower search costs. This study estimates the impact of nutrition label usage on Canadian consumers' ( n = 8,114) perceived diet-health concerns using alternative propensity score matching (PSM) techniques. We apply a series of tests and sensitivity analyses to overcome issues of endogeneity and selection bias frequently found in studies of diet-health behaviour and to validate the impact of exposure to nutrition facts labels for users vs. non-users. Our results support the notion that consumer uncertainty and related food-health concerns are linked to their information behaviour, but not in straightforward manner. Dominant subjective food attributes, such as taste, convenience and affordability, may in fact outweigh the benefits of information about healthier, alternative food choices. In order to change dietary health behaviour, food manufacturer and policy makers alike need to adopt communication instruments that better account for differences in preferences, shopping habits and overall usage patterns of nutrition labelling information. [ABSTRACT FROM AUTHOR]

Observational treatment studies provide a valuable alternative to RCTs but are often criticized due to potential self-selection biases. Studies comparing those who do and do not participate in research on eating disorder treatment are scarce, but necessary to evaluate the impact of self-selection bias on outcomes. All consecutive underweight adult first admissions ( N = 392) to an integrated inpatient (IP)-partial hospital (PH) behavioral specialty program were invited to participate in a longitudinal study of eating disorder treatment. Demographic and hospital course data were collected on participants ( n = 234) and non-participants ( n = 158). Participants and non-participants had similar BMI at admission, lengths of stay, and weight gain rates. Participants were less likely than non-participants to end treatment prematurely from IP and were discharged at a higher BMI; the effect size was small. Few differences in hospital course were observed between participants and non-participants. Although participants were more likely to transition to PH and were discharged at a higher BMI, completion of step-down to PH within this integrated IP-PH program rather than research participation status at admission was a better indicator of discharge BMI, which remains the strongest predictor of long-term weight-maintenance in eating disorders. [ABSTRACT FROM AUTHOR]

Background The objective of this study was to evaluate if mammography screening attendance is associated with a reduction in late-stage breast cancer incidence. Methods The cohort included over 400,000 Italian women who were first invited to participate in regional screening programmes during the 1990s and were followed for breast cancer incidence for 13 years. We obtained individual data on their exposure to screening and correlated this with total and stage-specific breast cancer incidence. Socio-economic status and pre-screening incidence data were used to assess the presence of self-selection bias. Results Overall, screening attendance was associated with a 10% excess risk of in situ and invasive breast cancer (IRR = 1.10; 95% confidence interval (CI): 1.06–1.14), which dropped to 5% for invasive cancers only (IRR = 1.05; 95% CI: 1.01–1.09). There were significant reductions among attenders for specific cancer stages; we observed a 39% reduction for T2 or larger (IRR = 0.61; 95% CI: 0.57–0.66), 19% for node positives (IRR = 0.81; 95% CI: 0.76–0.86) and 28% for stage II and higher (IRR = 0.72; 95% CI: 0.68–0.76). Our data suggest that the presence of self-selection bias is limited and, overall, invited women experienced a 17% reduction of advanced cancers compared with pre-screening rates. Conclusions Comparing attenders' and non-attenders' stage-specific breast cancer incidence, we have estimated that screening attendance is associated with a reduction of nearly 30% for stages II+. [ABSTRACT FROM AUTHOR]

The choice of irrigation water sources is crucial in rice farming as water availability and cost can vary across water sources. Groundwater caters three-quarters of the total irrigated land in Bangladesh, where rice area alone occupies 80% of the total irrigated land. The present study compares productivity and efficiency differences and determinants of surface and groundwater irrigation users based on a sample of 6947 dry-winter rice growing plots from the nationally representative Bangladesh Integrated Household Survey-2018 database. A range of methods was adopted to correct for heterogeneity in irrigation water source choice decision, self-selection and observable biases. This involved an estimation of a Stochastic Production Frontier (SPF) model with the pooled sample first, then an application of Propensity Score Matching (PSM) to remove self-selection and observable biases, then a test of heterogeneity in irrigation source choices was conducted, and finally estimated two SPF separately for matched samples of groundwater and surface water irrigation users. Results revealed a robust effect of groundwater irrigation in enhancing rice productivity and efficiency. Seed and its quality, fertilizer and soil type are also significant drivers of rice productivity. The significant drivers of efficiency are plot ownership, irrigation frequency, subsidy and family size. Large farms with groundwater-irrigated plots are relatively more efficient. Significantly lower efficiency exists in areas vulnerable to drought. These results raise sustainability concerns owing to the high level of groundwater extraction and falling water table. Policymakers need to devise innovative strategies to increase use of surface water irrigation without sacrificing productivity and efficiency, which has been a priority policy drive in Bangladesh. • Competitiveness of groundwater versus surface water for irrigation is evaluated. • Groundwater irrigation technology enhances rice productivity and efficiency. • Dominance of groundwater for irrigation raises environmental/sustainability concern. • Plot ownership, irrigation frequency, subsidy and family size drive efficiency. • Innovative strategies are required to encourage surface water irrigation technology. [ABSTRACT FROM AUTHOR]

Propensity score based methods applied to mitigate the bias in treatment effect estimation incurred by self-selection on observables, usually follow non-parametric matching approaches. Parametric estimation, performed by regressing solely on propensity scores, is suggested in theory, but is not generally applied. However, when appropriate, a parametric approach is preferable to a non-parametric or semi-parametric one as it provides more information, insight and inference on the same data set. We test parametric regression method through simulations, creating different scenarios of system-determined treatment assignment. It results that regressing only on propensity score, is not sufficient to properly mitigate the treatment estimation bias. We consider the propensity score as an omitted variable, which when added into the model, makes covariates and the binary treatment of interest conditionally independent. Propensity score enters the model as a generated regressor, because it is created in a separate modeling stage, and provides for unbiased and consistent estimation of treatment effects. This estimation is superior to the semi-parametric ones in our tests. Two real data with potential self-selection bias problems are analyzed to illustrate some application issues and to point out in particular the need for specific propensity scores application at any given situation. [ABSTRACT FROM AUTHOR]

In order to improve the rural labor productivity and farmers' income, land use transfer was launched and encouraged in recent years, especially the Thirteenth Five-Year Plan (2016-2020). This study aims to shed light on the impact of land use rights transfer on household labor productivity, based on a case study of Chongqing in China. Studies have revealed that land use transfer entails a process of self-selection and does not occur in a random manner. The study, therefore, addressed the issue of sample selection by applying propensity score matching. The study results suggested significant differences in the effects of land use transfer on household labor productivity. Specifically, renting land from other households had a positive effect on total labor productivity (TLP) and agricultural labor productivity (ALP). Moreover, TLP and ALP were found to be higher for households that rented more land or that were located in plain areas. Renting out land had a robust and positive effect on the TLP and non-agricultural labor productivity (NALP). TLP and NALP were also higher for households that rented out more land or that were located in plain areas. These findings suggest that land use transfer should be actively encouraged in plain areas. However, in mountainous areas, there is a need to pay more attention to expanding agriculture to benefit poor and marginalized populations in these areas. [ABSTRACT FROM AUTHOR]

Obtaining informed consent from individuals to participate in voluntary research studies is widely considered to be an ethical research practice. However, there is considerable debate over how consent should be obtained from subjects. Many researchers argue that active (opt-in) consent is the only type of consent that accurately reflects the true wishes of the subject and is closer to the informed consent ideal than passive (opt-out) consent procedures. Opponents of active consent procedures argue that such procedures harm study participation rates and increase the risk of self-selection bias to a greater extent than passive consent procedures. Empirical evaluations of these claims are rare, given the lack of studies that experimentally assign subjects to different consent procedures and utilize a control group (in which no consent is sought) to facilitate comparison. We report on an experiment that overcomes these issues in an study of consent to transfer contact data from a federal register to a third-party data collector for purposes of carrying out a telephone survey. Specifically, we evaluate the impact of requiring consent on survey participation rates, self-selection bias, and the resulting survey estimates. We find that the passive consent procedure does a better job of minimizing self-selection bias and maximizing the validity of the survey estimates (relative to the control group) compared with the active consent procedure. However, neither procedure is ideal: Both consent procedures increase the total self-selection bias and reduce the sample size. We conclude with a general discussion of the main findings and their practical implications. [ABSTRACT FROM AUTHOR]

In China, many rural migrant workers live in urbanising villages that are usually located in peripheral areas of major cities. Different from the spatial mismatch literature in which locations of minorities in the US are constrained by racial discrimination in the housing market, the residential segregation of rural migrant workers in China is largely due to China’s unique institutional context (e.g. land tenure system, hukou system) and the exclusionary housing regulations. Those living in these urbanising villages could incur both negative spatial mismatch effects and positive spillover effects. Through a survey across four mega-regions in China that are currently experiencing the most rapid urbanisation, we collect unique information on rural migrant workers’ attitudes towards living in urbanising villages, and therefore are able to address the self-selection bias that has broadly existed in many previous studies on residential segregation and spatial mismatch. The models show that the net effect of residential segregation in urbanising villages on migrant workers’ employment outcomes (both employment propensity and wage) appears to be positive, suggesting the spillover effects override the spatial mismatch effects. Current policy proposals by government officials to demolish urbanising villages should be accompanied by alternative policies to assist with housing migrant workers in appropriate locations that not only reduce spatial mismatch effects but also maintain positive spillover effects. [ABSTRACT FROM AUTHOR]

Scholars and planners have emphasized the importance of community spaces to enhance social capital in neighborhoods. This study extends the previous literature examining the influences of community centers on social capital in neighborhoods. Although prior research have estimated the association between community spaces uses and individual level of social capital, there is limited understanding of the causal direction of the effects of community spaces. This study fills this gap by employing the behavioral dissonance framework to clarify the effects of self-selection bias and/or actual effects of community center uses on social capital. Based on a household drop-off survey of 600 respondents in Seoul, Korea, we use a multiple regression model to identify the relationships between community center uses and overall social capital. Additionally, we take account of how the influences of community center use vary across different domains of social capital by employing ordinal logistic regression models. Our results may help planners and policymakers better understand how to enhance social capital with community spaces and develop tailored strategies to achieve social sustainability in regenerated neighborhoods according to different domains of social capital. • Explore the impacts of community center uses on social capital. • Specify how the impacts vary across different domains of social capital. • Employ the behavioral dissonance framework to clarify self-selection bias. • Community center use increases overall social capital. • Results vary across different domains of social capital and individual attitudes. [ABSTRACT FROM AUTHOR]