Using information from telephone panel surveys to predict reasons for refusal

One of the key problems in conducting surveys is convincing people to participate.¦However, it is often difficult or impossible to determine why people refuse. Panel surveys¦provide information from previous waves that can offer valuable clues as to why people¦refuse to participate. If we are able to anticipate the reasons for refusal, then we¦may be able to take appropriate measures to encourage potential respondents to participate¦in the survey. For example, special training could be provided for interviewers¦on how to convince potential participants to participate.¦This study examines different influences, as determined from the previous wave,¦on refusal reasons that were given by the respondents in the subsequent wave of the¦telephone Swiss Household Panel. These influences include socio-demography, social¦inclusion, answer quality, and interviewer assessment of question understanding and¦of future participation. Generally, coefficients are similar across reasons, and¦between-respondents effects rather than within-respondents effects are significant.¦While 'No interest' reasons are easier to predict, the other reasons are more situational. Survey-specific issues are able to distinguish¦different reasons to some extent.

A concentric analysis of the impact of urbanization on the threatened European tree frog in an agricultural landscape

Pond-breeding amphibians are affected by site-specific factors and regional and landscape-scale patterns of land use. Recent anthropogenic landscape modifications (drainage, agriculture intensification, larger road networks, and increased traffic) affect species by reducing the suitable habitat area and fragmenting remaining populations. Using a robust concentric approach based on permutation tests, we evaluated the impact of recent landscape changes on the presence of the endangered European tree frog (Hyla arborea.) in wetlands. We analyzed the frequency of 1 traffic and 14 land-use indices at 20 circular ranges (from 100-m up to 2-km radii) around 76 ponds identified in western Switzerland. Urban areas and road surfaces had a strong adverse effect on tree frog presence even at relatively great distances (from 100 m up to 1 km). When traffic measurements were considered instead of road surfaces, the effect increased, suggesting a negative impact due to a vehicle-induced effect. Altogether, our results indicate that urbanization and traffic must be taken into account when pond creation is an option in conservation management plans, as is the case for the European tree frog in western Switzerland. We conclude that our easy-to-use and robust concentric method of analysis can successfully assist managers in identifying potential sites for pond creation, where probability of the presence of tree frogs is maximized.

Effects of different Incentives on Attrition and Fieldwork Effort in Telephone Household Panel Surveys

Little is known about sample behavior and fieldwork effects of different incentives introduced in a household panel survey. This is especially true for telephone surveys. In a randomized experiment, the Swiss Household Panel implemented one prepaid and two promised nonmonetary incentives in the range of 10 to 15 Swiss Francs (7-10 e), plus a no incentive control group. The aim of the paper is to compare effects of these incentives especially on cooperation, but also on sample selection and fieldwork effort, separated by the household and the subsequent individual level. We find small positive cooperation effects of the prepaid incentive on both the household and the individual level especially in larger households. Sample composition is affected to a very minor extent. Finally, incentives tend to save fieldwork time and partially the number of contacts needed on the individual level.

Attrition of Households and Individuals in Panel Surveys

Attrition is mostly caused by not contacted or refusing sample members. On one hand it is well-known that reasons to attrite due to non-contact are different from those that are due to refusal. On the other hand does non-contact most probably affect household attrition, while refusal can be effective on both households and individuals. In this article, attrition on both the household and (conditional on household participation) the individual level is analysed in three panel surveys from the Cross National Equivalent File (CNEF): the German Socio- Economic Panel (GSOEP), the British Household Panel Study (BHPS), and the Swiss Household Panel (SHP). To follow households over time we use a common rule in all three surveys. First, we find different attrition magnitudes and patterns both across the surveys and also on the household and the individual level. Second, there is more evidence for reinforced rather than compensated household level selection effects if the individual level is also taken into account.

The Use of Passive Samplers to Reveal Industrial and Agricultural Pollution Trends in Swiss Rivers

This study shows the efficiency of passive sampling to reveal industrial and agricultural pollution trends. Two practical applications for nonpolar and polar contaminants are presented. Low-density polyethylene (LDPE) samplers were deployed for one year in the Venoge River (VD) to monitor indicator PCBs (iPCBs, IUPAC nos. 28, 52, 101, 138, 153 and 180). The results showed that the impact of PCB emissions into the river is higher in summer than in other seasons due to the low flow rate of the river during this period. P,olar organic chemical integrative samplers (POCIS) were deployed for 4 months in the Sion-Riddes canal (VS) to investigate herbicides (terbuthylazine, diuron and linuron). Desisopropylatrazine-d5 (DIA-d5) was tested as a performance reference compound (PRC) to estimate aqueous concentration. The results showed an increase of water contamination due to the studied agricultural area. The maximal contamination was observed in April and corresponds to the period of herbicide application on the crops.

Body mass index: comparing mean values and prevalence rates from telephone and examination surveys.

BACKGROUND: Cost effective means of assessing the levels of risk factors in the population have to be defined in order to monitor these factors over time and across populations. This study is aimed at analyzing the difference in population estimates of the mean levels of body mass index (BMI) and the prevalences of overweight, between health examination survey and telephone survey. METHODS: The study compares the results of two health surveys, one by telephone (N=820) and the other by physical examination (N=1318). The two surveys, based on independent random samples of the population, were carried out over the same period (1992-1993) in the same population (canton of Vaud, Switzerland). RESULTS: Overall participation rates were 67% and 53% for the health interview survey (HIS) and the health examination survey (HES) respectively. In the HIS, the reporting rate was over 98% for weight and height values. Self-reported weight was on average lower than measured weight, by 2.2 kg in men and 3.5 kg in women, while self-reported height was on average greater than measured height, by 1.2 cm in men and 1.9 cm in women. As a result, in comparison to HES, HIS led to substantially lower mean levels of BMI, and to a reduction of the prevalence rates of obesity (BMI>30 kg/m(2)) by more than a half. These differences are larger for women than for men. CONCLUSION: The two surveys were based on different sampling procedures. However, this difference in design is unlikely to explain the systematic bias observed between self-reported and measured values for height and weight. This bias entails the overall validity of BMI assessment from telephone surveys.

The social transition of risk factors for cardiovascular disease in the African region: evidence from three cross-sectional surveys in the Seychelles.

OBJECTIVES: To examine the association between socioeconomic status (SES) and several cardiovascular disease risk factors (CVRFs) and to assess whether this association has changed over a 15-year observation period. METHODS: Three independent population-based surveys of CVRFs were conducted in representative samples of all adults aged 25-64 years in the Seychelles, a small island state located east to Kenya, in 1989 (N=1081), 1994 (N=1067) and 2004 (N=1255). RESULTS: Among men, current smoking and heavy drinking were more prevalent in the low versus the high SES group, and obesity was less prevalent. The socioeconomic gradient in diabetes reversed over the study period from lower prevalence in the low versus the high SES group to higher prevalence in the low SES group. Hypercholesterolemia was less prevalent in the low versus the high SES group in 1989 but the prevalence was similar in the two groups in 2004. Hypertension showed no consistent socioeconomic pattern. Among women, the SES gradient in smoking tended to reverse over time from lower prevalence in the low SES group to lower prevalence in the high SES group. Obesity and diabetes were more common in the low versus the high SES group over the study period. Heavy drinking, hypertension and hypercholesterolemia were not socially patterned among women. CONCLUSION: The prevalence of several CVRFs was higher in low versus high SES groups in a rapidly developing country in the African region, and an increase of the burden of these CVRFs in the most disadvantaged groups of the population was observed over the 15 years study period.

National, regional, and global trends in fasting plasma glucose and diabetes prevalence since 1980: systematic analysis of health examination surveys and epidemiological studies with 370 country-years and 2·7 million participants.

BACKGROUND: Data for trends in glycaemia and diabetes prevalence are needed to understand the effects of diet and lifestyle within populations, assess the performance of interventions, and plan health services. No consistent and comparable global analysis of trends has been done. We estimated trends and their uncertainties in mean fasting plasma glucose (FPG) and diabetes prevalence for adults aged 25 years and older in 199 countries and territories. METHODS: We obtained data from health examination surveys and epidemiological studies (370 country-years and 2·7 million participants). We converted systematically between different glycaemic metrics. For each sex, we used a Bayesian hierarchical model to estimate mean FPG and its uncertainty by age, country, and year, accounting for whether a study was nationally, subnationally, or community representative. FINDINGS: In 2008, global age-standardised mean FPG was 5·50 mmol/L (95% uncertainty interval 5·37-5·63) for men and 5·42 mmol/L (5·29-5·54) for women, having risen by 0·07 mmol/L and 0·09 mmol/L per decade, respectively. Age-standardised adult diabetes prevalence was 9·8% (8·6-11·2) in men and 9·2% (8·0-10·5) in women in 2008, up from 8·3% (6·5-10·4) and 7·5% (5·8-9·6) in 1980. The number of people with diabetes increased from 153 (127-182) million in 1980, to 347 (314-382) million in 2008. We recorded almost no change in mean FPG in east and southeast Asia and central and eastern Europe. Oceania had the largest rise, and the highest mean FPG (6·09 mmol/L, 5·73-6·49 for men; 6·08 mmol/L, 5·72-6·46 for women) and diabetes prevalence (15·5%, 11·6-20·1 for men; and 15·9%, 12·1-20·5 for women) in 2008. Mean FPG and diabetes prevalence in 2008 were also high in south Asia, Latin America and the Caribbean, and central Asia, north Africa, and the Middle East. Mean FPG in 2008 was lowest in sub-Saharan Africa, east and southeast Asia, and high-income Asia-Pacific. In high-income subregions, western Europe had the smallest rise, 0·07 mmol/L per decade for men and 0·03 mmol/L per decade for women; North America had the largest rise, 0·18 mmol/L per decade for men and 0·14 mmol/L per decade for women. INTERPRETATION: Glycaemia and diabetes are rising globally, driven both by population growth and ageing and by increasing age-specific prevalences. Effective preventive interventions are needed, and health systems should prepare to detect and manage diabetes and its sequelae. FUNDING: Bill & Melinda Gates Foundation and WHO.

Beyond the insiders' circle: disseminating the results of adolescent health surveys.

Adolescent health surveys, like those for other segments of the population, tend to remain in the hands of researchers, where they can have no real impact on the way critical health issues are dealt with by policy makers or other professionals directly connected to young people in their everyday work. This paper reviews important issues concerning the dissemination of survey results among professionals from various fields. The content, length and wording of the messages should be tailored to the audience one wants to reach as well as the type of channels used for their diffusion. Survey data sets can be used to select priorities for interventions: ad hoc presentations, attractive summaries and brochures, or even films expressing young peoples' opinions have been used by European public health professionals to make data sets usable in various local, regional and national contexts. CONCLUSION: The impact of these diffusion strategies is, however, difficult to assess and needs to be refined. The adequate delivery of survey findings as well as advocacy and lobbying activities require specific skills which can be endorsed by specialized professionals. Ultimately, it is the researchers' responsibility to ensure that such tasks are effectively performed.

Cooperation in centralised CATI Household Panel Surveys : A Contact-based Multilevel Analysis to Examine Interviewer, Respondent, and Fieldwork Process Effects

In this research, we analyse the contact-specific mean of the final cooperation probability, distinguishing on the one hand between contacts with household reference persons and with other eligible household members, and on the other hand between first and later contacts. Data comes from two Swiss Household Panel surveys. The interviewer-specific variance is higher for first contacts, especially in the case of the reference person. For later contacts with the reference person, the contact-specific variance dominates. This means that interaction effects and situational factors are decisive. The contact number has negative effects on the performance of contacts with the reference person, positive in the case of other persons. Also time elapsed since the previous contact has negative effects in the case of reference persons. The result of the previous contact has strong effects, especially in the case of the reference person. These findings call for a quick completion of the household grid questionnaire, assigning the best interviewers to conducting the first contact. While obtaining refusals has negative effects, obtaining other contact results has only weak effects on the interviewer's subsequent contact outcome. Using the same interviewer for contacts has no positive effects.