Analysis of non-response bias in a mailed health survey
ABSTRACT The objective of this study was to identify characteristics of non-respondents and late respondents to a mailed health survey. Persons who returned and those who did not return the questionnaire were compared using health insurance data, which indicated their age, sex, and health care expenditures in the previous year. Insurance and questionnaire data were used to compare early and late survey respondents and to compare categories of non-respondents. Questions covered use of health services, health status, and sociodemographic characteristics. Participants were members of health insurance plans in Geneva, Switzerland, 19–45 years old (n = 1822). Respondents (n = 1424) and non-respondents (n = 398) were of similar age and sex. The proportion of persons who had health care expenditures greater than zero Swiss francs (SFr) was higher among respondents (75%) than among non-respondents (69%, p = 0.03). Among non-respondents, expenditures of persons who explicitly refused to participate (2378 SFr) were higher than expenditures of persons who moved out of Geneva (1085 SFr) or who failed to return the questionnaire (1592 SFr, p = 02). Among respondents, being born in a Switzerland, having completed elementary school, having generated health care expenditures, and reporting good physical health were independent predictors of early response. In conclusion, low response rates to mailed health surveys may result in overestimating the utilization of health services. However, non-respondents did not constitute a homogenous group, and the strength and even direction of non-response bias depended on the mechanisms of non-response.
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ABSTRACT: The environmental movement has emerged as a response to society's concerns about the sustainability of Earth's natural resources and the effects of human activity on the environment and on society's well-being. Effects such as deforestation, air and water pollution, and resource depletion have shown to cause a decline in the quality of life of humans. In response, concerned citizens, non-governmental organizations, and governments have started initiatives to ensure the responsible utilization of our natural resources. Two of these initiatives in particular are relevant for U.S. hardwood products manufacturers: forest certification systems and green building standards. The former are standards created with the purpose of ensuring the sustainable utilization of the forest resource. Most forest certification systems also offer a chain-of-custody certification, to assure customers that label-carrying products indeed originate from certified forests. Green building standards were created to reduce the environmental impact caused by building construction and use.This paper presents the results from a survey of U.S. hardwood lumber manufacturers, with the objective of learning about the industry's awareness and perceptions about forest certification and green building systems and the impact of the environmental movement on the industry. Questions asked ranged from familiarity with different systems for forest certification and green building standards to these systems' financial and market impact on hardwood lumber industry participants. Responses show that industry participants are more familiar with forest certification systems than with green building standards. Among forest certification systems, the Sustainable Forest Initiative (SFI) is the most recognized, followed by the Forest Stewardship Council (FSC). Almost 30 percent of respondents reported holding some type of chain of custody (COC) certification and 26 percent stated that obtaining certification was in their plans. Out of the respondents who participated in COC certification at the time of the study, only 25 percent reported having benefited financially from it. Awareness with green building standards among respondents is low in general, but the Leadership in Energy and Environmental Design (LEED) and the National Green Building Standard were the most recognized. When asked what the industry should do to obtain the maximum benefits from the environmental movement, most respondents, 36 percent, suggested that the industry should do more to educate the public on the environmentally-friendly nature of hardwood products.Journal of Cleaner Production 09/2012; 33:30-41. · 3.59 Impact Factor
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ABSTRACT: Abstract This paper reports result from a survey on 157 navigators (bridge officers) from eight offshore companies operating in the North Sea. The questionnaire measured stress, work pressure and sleep/rest (fatigue). Sleep/rest and work pressure explained around 35% of the variation in stress. Work pressure increases stress, and sleep and rest reduce stress both directly and through reduced work pressure. A positive work climate/supportive culture reduces stress on the bridge substantially through reducing work pressure and improving sleep and rest quality. The research indicates that age and the length of time that respondents have been seafarers do not have any influence on stress. However, a significant difference at the 10% significance level was found in relation to occupation (between first mate and other navigators). Around 30% of the respondents reported unsatisfactory sleep and rest during a normal day. More than 10% of the respondents reported that senior management was not interested in their health and safety, and more than 15% of the officers reported that they took short cuts to get their work done.Safety Science 01/2015; Volume 71, Part B(January 2015):160 -166. · 1.67 Impact Factor
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ABSTRACT: Objectives Conducting health surveys with community-based random samples are essential to capture an otherwise unreachable population, but these surveys can be biased if the effort to reach participants is insufficient. This study determines the desirable amount of effort to minimise such bias. Design A household-based health survey with random sampling and face-to-face interviews. Up to 11 visits, organised by canvassing rounds, were made to obtain an interview. Setting Single-family homes in an underserved and understudied population in North Miami-Dade County, Florida, USA. Participants Of a probabilistic sample of 2200 household addresses, 30 corresponded to empty lots, 74 were abandoned houses, 625 households declined to participate and 265 could not be reached and interviewed within 11 attempts. Analyses were performed on the 1206 remaining households. Primary outcome Each household was asked if any of their members had been told by a doctor that they had high blood pressure, heart disease including heart attack, cancer, diabetes, anxiety/ depression, obesity or asthma. Responses to these questions were analysed by the number of visit attempts needed to obtain the interview. Results Return per visit fell below 10% after four attempts, below 5% after six attempts and below 2% after eight attempts. As the effort increased, household size decreased, while household income and the percentage of interviewees active and employed increased; proportion of the seven health conditions decreased, four of which did so significantly: heart disease 20.4–9.2%, high blood pressure 63.5–58.1%, anxiety/depression 24.4–9.2% and obesity 21.8–12.6%. Beyond the fifth attempt, however, cumulative percentages varied by less than 1% and precision varied by less than 0.1%. Conclusions In spite of the early and steep drop, sustaining at least five attempts to reach participants is necessary to reduce selection bias.BMJ Open 01/2014; 4(12):e005791. · 2.06 Impact Factor