Identifying Pertinent Variables for Nonresponse Follow-Up Surveys : Lessons Learned from 4 Cases in Switzerland

All social surveys suffer from different types of errors, of which one of the most studied is non-response bias. Non-response bias is a systematic error that occurs because individuals differ in their accessibility and propensity to participate in a survey according to their own characteristics as well as those from the survey itself. The extent of the problem heavily depends on the correlation between response mechanisms and key survey variables. However, non-response bias is difficult to measure or to correct for due to the lack of relevant data about the whole target population or sample. In this paper, non-response follow-up surveys are considered as a possible source of information about non-respondents. Non-response follow-ups, however, suffer from two methodological issues: they themselves operate through a response mechanism that can cause potential non-response bias, and they pose a problem of comparability of measure, mostly because the survey design differs between main survey and non-response follow-up. In order to detect possible bias, the survey variables included in non-response surveys have to be related to the mechanism of participation, but not be sensitive to measurement effects due to the different designs. Based on accumulated experience of four similar non-response follow-ups, we studied the survey variables that fulfill these conditions. We differentiated socio-demographic variables that are measurement-invariant but have a lower correlation with non-response and variables that measure attitudes, such as trust, social participation, or integration in the public sphere, which are more sensitive to measurement effects but potentially more appropriate to account for the non-response mechanism. Our results show that education level, work status, and living alone, as well as political interest, satisfaction with democracy, and trust in institutions are pertinent variables to include in non-response follow-ups of general social surveys. - See more at: https://ojs.ub.uni-konstanz.de/srm/article/view/6138#sthash.u87EeaNG.dpuf

Validity of silhouette showcards as a measure of body size and obesity in a population in the African region : a practical research tool for general-purpose surveys.

BACKGROUND: The purpose of this study is to validate the Pulvers silhouette showcard as a measure of weight status in a population in the African region. This tool is particularly beneficial when scarce resources do not allow for direct anthropometric measurements due to limited survey time or lack of measurement technology in face-to-face general-purpose surveys or in mailed, online, or mobile device-based surveys. METHODS: A cross-sectional study was conducted in the Republic of Seychelles with a sample of 1240 adults. We compared self-reported body sizes measured by Pulvers' silhouette showcards to four measurements of body size and adiposity: body mass index (BMI), body fat percent measured, waist circumference, and waist to height ratio. The accuracy of silhouettes as an obesity indicator was examined using sex-specific receiver operator curve (ROC) analysis and the reliability of this tool to detect socioeconomic gradients in obesity was compared to BMI-based measurements. RESULTS: Our study supports silhouette body size showcards as a valid and reliable survey tool to measure self-reported body size and adiposity in an African population. The mean correlation coefficients of self-reported silhouettes with measured BMI were 0.80 in men and 0.81 in women (P < 0.001). The silhouette showcards also showed high accuracy for detecting obesity as per a BMI ≥ 30 (Area under curve, AUC: 0.91/0.89, SE: 0.01), which was comparable to other measured adiposity indicators: fat percent (AUC: 0.94/0.94, SE: 0.01), waist circumference (AUC: 0.95/0.94, SE: 0.01), and waist to height ratio (AUC: 0.95/0.94, SE: 0.01) amongst men and women, respectively. The use of silhouettes in detecting obesity differences among different socioeconomic groups resulted in similar magnitude, direction, and significance of association between obesity and socioeconomic status as when using measured BMI. CONCLUSIONS: This study highlights the validity and reliability of silhouettes as a survey tool for measuring obesity in a population in the African region. The ease of use and cost-effectiveness of this tool makes it an attractive alternative to measured BMI in the design of non-face-to-face online- or mobile device-based surveys as well as in-person general-purpose surveys of obesity in social sciences, where limited resources do not allow for direct anthropometric measurements.

Serological and virological surveys of the influenza A viruses in Antarctic and sub-Antarctic penguins

To evaluate the avian influenza virus (AIV) circulation in Antarctic and sub-Antarctic penguins we carried out a serosurvey on six species from Livingston, Marion and Gough islands. Seropositivity against AIV was performed on serum samples using a competitive enzyme-linked immunosorbent assay and haemagglutination and neuraminidase inhibition assays. Some oropharyngeal and cloacal swabs were also assayed to detect influenza virus genomes by real time reverse transcription-polymerase chain reaction. Overall, 12.1% (n = 140) penguins were seropositive to AIV. By species, we detected 5% (n = 19) and 11% (n = 18) seroprevalence in sub-Antarctic rockhopper penguins (Eudyptes spp.) from Gough and Marion islands, respectively, 42% (n = 33) seroprevalence in macaroni penguins (Eudyptes chysolophus Brandt), but no positives in the three other species, gentoo (Pygoscelis papua Forster; n = 25) and chinstrap penguins (P. antarctica Forster; n = 16), from Livingston Island and king penguins (Aptenodytes patagonicus Miller; n = 27) from Marion Island. While seropositivity reflected previous exposure to the AIV, the influenza genome was not detected. Our results indicate that AIV strains have circulated in penguin species in the sub-Antarctic region, but further studies are necessary to determine the precise role that such penguin species play in AIV epidemiology and if this circulation is species (or genus) specific.

Calculation of the variance in surveys of the economic climate

Public opinion surveys have become progressively incorporated into systems of official statistics. Surveys of the economic climate are usually qualitative because they collect opinions of businesspeople and/or experts about the long-term indicators described by a number of variables. In such cases the responses are expressed in ordinal numbers, that is, the respondents verbally report, for example, whether during a given trimester the sales or the new orders have increased, decreased or remained the same as in the previous trimester. These data allow to calculate the percent of respondents in the total population (results are extrapolated), who select every one of the three options. Data are often presented in the form of an index calculated as the difference between the percent of those who claim that a given variable has improved in value and of those who claim that it has deteriorated.

Phytosociological surveys: tools for weed science?

In simple terms, a phytosociological survey is a group of ecological evaluation methods whose aim is to provide a comprehensive overview of both the composition and distribution of plant species in a given plant community. To understand the applicability of phytosociological surveys for weed science, as well as their validity, their ecological basis should be understood and the most suitable ones need to be chosen, because cultivated fields present a relatively distinct group of selecting factors when compared to natural plant communities. For weed science, the following sequence of steps is proposed as the most suitable: (1) overall infestation; (2) phytosociological tables/graphs; (3) intra-characterization by diversity; (4) inter-characterization and grouping by cluster analysis. A summary of methods is established in order to assist Weed Science researchers through their steps into the realm of phytosociology.

Floristic surveys of aquatic macrophytes in reservoirs in the Agreste zone of Pernambuco State, Brazil

We surveyed the aquatic macrophytes in reservoirs in Camocim de São Félix in the Agreste zone of Pernambuco State, Brazil. Plants were collected on a bimonthly schedule from November/2008 to May/2009 in four reservoirs, and 33 taxa distributed among 23 families were encountered. The family Cyperaceae had the greatest number of species, followed by Lemnaceae. The predominant biologic form was emergent (33.3%) reflecting the extensive shorelines around the reservoirs analyzed.

Solar Twins and Solar Analogues in Galactic Surveys.

The Sun is a crucial benchmark for how we see the universe. Especially when it comes to the visible range of the spectrum, stars are commonly compared to the Sun, as it is the most thoroughly studied star. In this work I have focussed on two aspects of the Sun and how it is used in modern astronomy. Firstly, I try to answer the question on how similar to the Sun another star can be. Given the limits of observations, we call a solar twin a star that has the same observed parameters as the Sun within its errors. These stars can be used as stand-in suns when doing observations, as normal night-time telescopes are not built to be pointed at the Sun. There have been many searches for these twins and every one of them provided not only information on how close to the Sun another star can be, but also helped us to understand the Sun itself. In my work I have selected _ 300 stars that are both photometrically and spectroscopically close to the Sun and found 22 solar twins, of which 17 were previously unknown and can therefore help the emerging picture on solar twins. In my second research project I have used my full sample of 300 solar analogue stars to check the temperature and metallicity scale of stellar catalogue calibrations. My photometric sample was originally drawn from the Geneva-Copenhagen-Survey (Nordström et al. 2004; Holmberg et al. 2007, 2009) for which two alternative calibrations exist, i.e. GCS-III (Holmberg et al. 2009) and C11 (Casagrande et al. 2011). I used very high resolution spectra of solar analogues, and a new approach to test the two calibrations. I found a zero–point shift of order of +75 K and +0.10 dex in effective temperature and metallicity, respectively, in the GCS-III and therefore favour the C11 calibration, which found similar offsets. I then performed a spectroscopic analysis of the stars to derive effective temperatures and metallicities, and tested that they are well centred around the solar values.

Central Spitsbergen from sketch surveys made in 1896 and 1897

Kartta kuuluu A. E. Nordenskiöldin kokoelmaan

Map of the sources of Snake River : with its tributaries together with portions of the headwaters of the Madison and Yellowstone from surveys and observations of the Snake River Expedition

Kartta kuuluu A. E. Nordenskiöldin kokoelmaan

Map of the sources of Snake River : with its tributaries together with portions of the headwaters of the Madison and Yellowstone from surveys and observations of the Snake River Expedition

Kartta kuuluu A. E. Nordenskiöldin kokoelmaan

Geological sketch map of New Zealand constructed from official surveys and the explorations of F. von Hochstetter, Julius Haast and others

Kartta kuuluu A. E. Nordenskiöldin kokoelmaan

The Arctic Ocean between Greenland and Nova Zemla and between the 60th and 82d parallel of latitude from Swedish, Danish, British, Russian and German surveys and explorations up to 1871

Kartta kuuluu A. E. Nordenskiöldin kokoelmaan

India : west coast : Gulf of Cutch to Viziadrig from surveys by the officers of the East India government 1828-1856

Kartta kuuluu A. E. Nordenskiöldin kokoelmaan