WP 76 - Comparing different weighting procedures for volunteer web surveys

The strengths and weaknesses of web surveys have been widely described in the literature. Of particular interest is the question to which degree the obtained results can be generalised for the whole population? To deal with this problem weighting adjustments, like post-stratification and propensity score adjustment (PSA) have been seen as a possible solution. In the scientific community, however, particularly PSA has traditionally not been applied in the field of surveys, and there has been a minimal amount of evidence for its applicability and performance, and the implications are not conclusive. Against this background, the paper attempts to explore the two statistical weighting procedures for the German and Dutch WageIndicator Survey 2006. To evaluate the effectiveness of the weighting techniques in adjusting biases arising from non-randomised sample selection, the existing selection bias has been explored and the efficiency of the weights has be tested by comparing un-weighted and weighted results with those that could be found using data from the German SOEP and the Dutch OSA Panel for the same year. The results reveal that the impact of the applied weights is very limited and that the different weighting methods using balancing variables do not make web survey data more comparable to the general population. This holds for the German as well as for the Dutch sample.

Gender differentiation in higher education: educational specialization and labour market risks in Spain and Germany

The objective of this paper is to investigate the relationship between gender differentiation in tertiary education and labour market hazards. We analyze how differences between male and female tertiary graduates in the chosen degree level and field of study affect the likelihood to be unemployed or obtain a low status job. In order to learn about the role of institutional context, we compare Germany and Spain, two countries that differ with respect to horizontal (field of study) and vertical (degree level) segregation by gender as well as to the linkage between the education and labour market system. Using Labour Force Survey data from the year 2000, our results of logistic regression models as well as a non-linear decomposition technique generally confirm our expectation that the field of study explains a sizable portion of the gender gap in unemployment and low status jobs in both countries. Whereas the level of tertiary degree does not matter with respect to unemployment in either country, it explains part of the female disadvantage in holding a low status job in Spain. Moreover, our analyses show that women with a degree in a predominantly male field of study are not systematically disadvantaged compared to men. Finally, even though the role of the institutional context is hard to evaluate, it seems that, for the two selected countries, the horizontal and vertical gender segregation is more relevant in Spain than in Germany.' [author's abstract

Assessment of human immediate response capability related to tsunami threats in Indonesia at a sub-national scale

Human immediate response is contextualized into different time compartments reflecting the tsunami early warning chain. Based on the different time compartments the available response time and evacuation time is quantified. The latter incorporates accessibility of safe areas determined by a hazard assessment, as well as environmental and demographic impacts on evacuation speed properties assessed using a Cost Distance Weighting GIS approach. Approximately 4.35 million Indonesians live in tsunami endangered areas on the southern coasts of Sumatra, Java and Bali and have between 20 and 150 min to reach a tsunami-safe area. Most endangered areas feature longer estimated-evacuation times and hence the population possesses a weak immediate response capability leaving them more vulnerable to being directly impacted by a tsunami. At a sub-national scale these hotspots were identified and include: the Mentawai islands off the Sumatra coast, various sub-districts on Sumatra and west and east Java. Based on the presented approach a temporal dynamic estimation of casualties and displacements as a function of available response time is obtained for the entire coastal area. As an example, a worst case tsunami scenario for Kuta (Bali) results in casualties of 25 000 with an optimal response time (direct evacuation when receiving a tsunami warning) and 120 000 for minimal response time (no evacuation). The estimated casualties correspond well to observed/reported values and overall model uncertainty is low with a standard error of 5%. The results obtained allow for prioritization of intervention measures such as early warning chain, evacuation and contingency planning, awareness and preparedness strategies down to a sub-district level and can be used in tsunami early warning decision support

Webdatanet : Innovation and quality in web-based data collection

The article discusses the development of WEBDATANET established in 2011 which aims to create a multidisciplinary network of web-based data collection experts in Europe. Topics include the presence of 190 experts in 30 European countries and abroad, the establishment of web-based teaching and discussion platforms and working groups and task forces. Also discussed is the scope of the research carried by WEBDATANET. In light of the growing importance of web-based data in the social and behavioral sciences, WEBDATANET was established in 2011 as a COST Action (IS 1004) to create a multidisciplinary network of web-based data collection experts: (web) survey methodologists, psychologists, sociologists, linguists, economists, Internet scientists, media and public opinion researchers. The aim was to accumulate and synthesize knowledge regarding methodological issues of web-based data collection (surveys, experiments, tests, non-reactive data, and mobile Internet research), and foster its scientific usage in a broader community

Task implementation heterogeneity and wage dispersion

Wage dispersion among observationally similar workers is still only partially unexplained by economists from both a theoretical and an empirical point of view. Given that jobs can be broken down into tasks, namely units of work activities producing output, we empirically test whether part of the observed variation in wages across similar individuals is related to differences in the intensity with which tasks are implemented. We then investigate whether the variety in task implementation shown across occupations is related to cross-occupation wage levels. We found that the variation in task implementation in different occupations is related both to within-occupation wage dispersion and to cross-occupation wage levels: workers in high-wage occupations are less defined around a typical worker than those in other occupations

Automated seamless DNA co-transformation cloning with direct expression vectors applying positive or negative insert selection

<p>Abstract</p> <p>Background</p> <p>Molecular DNA cloning is crucial to many experiments and with the trend to higher throughput of modern approaches automated techniques are urgently required. We have established an automated, fast and flexible low-cost expression cloning approach requiring only vector and insert amplification by PCR and co-transformation of the products.</p> <p>Results</p> <p>Our vectors apply positive selection for the insert or negative selection against empty vector molecules and drive strong expression of target proteins in <it>E.coli </it>cells. Variable tags are available both in N-terminal or C-terminal position. A newly developed β-lactamase (ΔW290) selection cassette contains a segment inside the β-lactamase open reading frame encoding a stretch of hydrophilic amino acids that result in a T7 promoter when back-translated. This position of the promoter permits positive selection and attenuated expression of fusion proteins with C-terminal tags. We have tested eight vectors by inserting six target sequences of variable length, provenience and function. The target proteins were cloned, expressed and detected using an automated Tecan Freedom Evo II liquid handling work station. Only two colonies had to be picked to score with 85% correct inserts while 80% of those were positive in expression tests.</p> <p>Conclusions</p> <p>Our results establish co-transformation and positive/negative selection cloning in conjunction with the provided vectors and selection cassettes as an automatable alternative to commercialized high-throughput cloning systems like Gateway^®or ligase-independent cloning (LIC) <b/>.</p

Mosaic Genome Architecture of the Anopheles gambiae Species Complex

Attempts over the last three decades to reconstruct the phylogenetic history of the Anopheles gambiae species complex have been important for developing better strategies to control malaria transmission.We used fingerprint genotyping data from 414 field-collected female mosquitoes at 42 microsatellite loci to infer the evolutionary relationships of four species in the A. gambiae complex, the two major malaria vectors A. gambiae sensu stricto (A. gambiae s.s.) and A. arabiensis, as well as two minor vectors, A. merus and A. melas.We identify six taxonomic units, including a clear separation of West and East Africa A. gambiae s.s. S molecular forms. We show that the phylogenetic relationships vary widely between different genomic regions, thus demonstrating the mosaic nature of the genome of these species. The two major malaria vectors are closely related and closer to A. merus than to A. melas at the genome-wide level, which is also true if only autosomes are considered. However, within the Xag inversion region of the X chromosome, the M and two S molecular forms are most similar to A. merus. Near the X centromere, outside the Xag region, the two S forms are highly dissimilar to the other taxa. Furthermore, our data suggest that the centromeric region of chromosome 3 is a strong discriminator between the major and minor malaria vectors.Although further studies are needed to elucidate the basis of the phylogenetic variation among the different regions of the genome, the preponderance of sympatric admixtures among taxa strongly favor introgression of different genomic regions between species, rather than lineage sorting of ancestral polymorphism, as a possible mechanism

The kinematics of late type stars in the solar cylinder studied with SDSS data

We study the velocity distribution of Milky Way disk stars in a kiloparsec-sized region around the Sun, based on ~ 2 million M-type stars from DR7 of SDSS, which have newly re-calibrated absolute proper motions from combining SDSS positions with the USNO-B catalogue. We estimate photometric distances to all stars, accurate to ~ 20 %, and combine them with the proper motions to derive tangential velocities for this kinematically unbiased sample of stars. Based on a statistical de-projection method we then derive the vertical profiles (to heights of Z = 800 pc above the disk plane) for the first and second moments of the three dimensional stellar velocity distribution. We find that = -7 +/- 1 km/s and = -9 +/- 1 km/s, independent of height above the mid-plane, reflecting the Sun's motion with respect to the local standard of rest. In contrast, changes distinctly from -20 +/- 2 km/s in the mid-plane to = -32 km/s at Z = 800 pc, reflecting an asymmetric drift of the stellar mean velocity that increases with height. All three components of the M-star velocity dispersion show a strong linear rise away from the mid-plane, most notably \sigma_{ZZ}, which grows from 18 km/s (Z = 0) to 40 km/s (at Z = 800 pc). We determine the orientation of the velocity ellipsoid, and find a significant vertex deviation of 20 to 25 degrees, which decreases only slightly to heights of Z = 800 pc. Away from the mid-plane, our sample exhibits a remarkably large tilt of the velocity ellipsoid towards the Galactic plane, which reaches 20 deg. at Z = 800 pc and which is not easily explained. Finally, we determine the ratio \sigma^2_{\phi\phi}/\sigma^2_{RR} near the mid-plane, which in the epicyclic approximation implies an almost perfectly flat rotation curve at the Solar radius.Comment: 18 pages, 9 figures, accepted to Astron.

De impact van de versoepeling van het bezoekverbod op bewoners van verpleeghuizen en woonzorgcentra: Een vergelijking tussen mei en juni/juli 2020

Deze factsheet beschrijft de situatie van bewoners in instellingen voor verpleging en verzorging tijdens en na het beëindigen van het landelijke bezoekverbod in 2020. In mei en juni/juli is online vragenlijst onderzoek uitgevoerd naar de gevolgen van sociale isolatie door het nieuwe coronavirus in verpleeghuizen en woonzorgcentra. Voor beide metingen zijn deelnemers (bewoners, familieleden en zorgmedewerkers) onafhankelijk van elkaar geworven. Over het algemeen werd kwaliteit van leven in juni/juli vaker belangrijk gevonden dan veiligheid, en leken deelnemers meer bereid dan in mei om het risico van besmettingen te accepteren door bezoek toe te laten. Hoewel bewoners weer twee tot drie keer per week bezoek konden ontvangen, waren zij niet per se minder eenzaam. Wel werden positieve veranderingen in stemming en gedragsproblemen van bewoners gerapporteerd door familieleden en medewerkers. Ook kwaliteit van leven van bewoners werd beter gewaardeerd dan tijdens het bezoekverbod, maar was nog niet op het niveau als vóór het bezoekverbod. De positieve impact van de versoepeling van het bezoekverbod op bewoners, was al na een relatief korte periode zichtbaar. De resultaten ondersteunen de beslissing geen landelijk bezoekverbod meer in te stellen

Insight Into the Formation of the Milky Way Through Cold Halo Substructure. I. The ECHOS of Milky Way Formation

We identify ten -- seven for the first time -- elements of cold halo substructure (ECHOS) in the volume within 17.5 kpc of the Sun in the inner halo of the Milky Way. Our result is based on the observed spatial and radial velocity distribution of metal-poor main sequence turnoff (MPMSTO) stars in 137 Sloan Extension for Galactic Understanding and Exploration (SEGUE) lines of sight. We point out that the observed radial velocity distribution is consistent with a smooth stellar component of the Milky Way's inner halo overall, but disagrees significantly at the radial velocities that correspond to our detections. We show that all of our detections are statistically significant and that we expect no false positives. We also use our detections and completeness estimates to infer a formal upper limit of 0.34 +/- 0.02 on the fraction of the MPMSTO population in the inner halo that belong to ECHOS. Our detections and completeness calculations suggest that there is a significant population of low fractional overdensity ECHOS in the inner halo, and we predict that 1/3 of the inner halo (by volume) harbors ECHOS with MPMSTO star number densities n ~ 15 kpc^-3. ECHOS are likely older than known surface brightness substructure, so our detections provide us with a direct measure of the accretion history of the Milky Way in a region and time interval that has yet to be fully explored. In concert with previous studies, our result suggests that the level of merger activity has been roughly constant over the past few Gyr and that there has been no accretion of single stellar systems more massive than a few percent of a Milky Way mass in that interval. (abridged)Comment: 47 pages, 23 figures, and 6 tables in emulaetapj format; accepted for publication in Ap