Interval-level measurement with visual analogue scales in Internet-based research: VAS Generator

The present article describes VAS Generator (www.vasgenerator.net), a free Web service for creating a wide range of visual analogue scales that can be used as measurement devices in Web surveys and Web experimentation, as well as for local computerized assessment. A step-by-step example for creating and implementing a visual analogue scale with visual feedback is given. VAS Generator and the scales it generates work independently of platforms and use the underlying languages HTML and JavaScript. Results from a validation study with 355 participants are reported and show that the scales generated with VAS Generator approximate an interval-scale level. In light of previous research on visual analogue versus categorical (e.g., radio button) scales in Internet-based research, we conclude that categorical scales only reach ordinal-scale level, and thus visual analogue scales are to be preferred whenever possibl

Online- und Offlinevergleich visueller Analogskalen mit 4- und 8-stufig skalierten Likert-Skalen bei einem Fragebogen zum Verhalten in sozialen Gruppen

"Eine visuelle Analogskala (VAS) ist eine in der Regel 100 mm lange horizontale Linie mit verbalen Ankern an den Enden. Durch Setzen eines Kreuzes zwischen den Extremen kann das Ausmaß der Zustimmung zu einer Aussage wesentlich differenzierter zum Ausdruck gebracht werden als bei Likert-skalierten Items, die in den meisten Fällen nur zwischen vier und acht Abstufungen zulassen. Die Digitalisierung visueller Analogskalen beseitigt deren praktischen Hauptnachteil den erheblichen Aufwand durch manuelle Bestimmung der Position des vom Befragten gesetzten Kreuzes - durch das automatische Auslesen der Itemwerte und macht deren Anwendung für die empirische Sozialforschung (wieder) interessant. Da VAS in der Onlineforschung erstmalig in großen Umfang unkompliziert zum Einsatzkommen können, besteht besonderer Bedarf, sich mit den methodischen Vor- und Nachteilen dieser Skala zu beschäftigen. Ziel der Untersuchung ist es zu zeigen, wie sich VAS und Likert-Skalen (LS) zueinander verhalten und ob die aus Papier-und-Bleistift-Erhebungen gewonnenen methodischen Ergebnisse auch auf den Bereich der Onlineforschung übertragbar sind. Eine Voruntersuchung, bei der denselben Personen bei identischen Fragen sowohl fünf-stufige LS als auch VAS zur Bewertung vorgelegt wurden, ergab, dass die Randkategorien bei Likert-skalierten Items deutlich seltener belegt wurden als bei VAS, während sich die Belegung der mittleren Kategorien kaum unterschied. Für die Hauptuntersuchung (auf http://www.web-experiment.nonfx.net ) wurde ein Fragebogen mit 16 Items zum Verhalten in sozialen Gruppen verwendet. Durch den Vergleich von VAS mit sowohl vier- als auch acht-stufigen LS sollen Widersprüche zwischen den bisher publizierten Ergebnissen (bei denen die Breite der verwendeten LS zwischen vier und zehn Kategorien schwankt) erklärbar werden. Es wird der Frage nachgegangen, ob es Schwierigkeiten bei der Übertragung der Ergebnisse gibt, ob die Kategorien der LS äquidistant wahrgenommen werden und schließlich ob visuelle Analogskalen eine Alternative zu Likert-Skalen darstellen." (Autorenreferat

Ambient-noise tomography of the wider Vienna Basin region

We present a new 3-D shear-velocity model for the top 30 km of the crust in the wider Vienna Basin region based on surface waves extracted from ambient-noise cross-correlations. We use continuous seismic records of 63 broad-band stations of the AlpArray project to retrieve interstation Green’s functions from ambient-noise cross-correlations in the period range from 5 to 25 s. From these Green’s functions, we measure Rayleigh group traveltimes, utilizing all four components of the cross-correlation tensor, which are associated with Rayleigh waves (ZZ, RR, RZ and ZR), to exploit multiple measurements per station pair. A set of selection criteria is applied to ensure that we use high-quality recordings of fundamental Rayleigh modes. We regionalize the interstation group velocities in a 5 km × 5 km grid with an average path density of ∼20 paths per cell. From the resulting group-velocity maps, we extract local 1-D dispersion curves for each cell and invert all cells independently to retrieve the crustal shear-velocity structure of the study area. The resulting model provides a previously unachieved lateral resolution of seismic velocities in the region of ∼15 km. As major features, we image the Vienna Basin and Little Hungarian Plain as low-velocity anomalies, and the Bohemian Massif with high velocities. The edges of these features are marked with prominent velocity contrasts correlated with faults, such as the Alpine Front and Vienna Basin transfer fault system. The observed structures correlate well with surface geology, gravitational anomalies and the few known crystalline basement depths from boreholes. For depths larger than those reached by boreholes, the new model allows new insight into the complex structure of the Vienna Basin and surrounding areas, including deep low-velocity zones, which we image with previously unachieved detail. This model may be used in the future to interpret the deeper structures and tectonic evolution of the wider Vienna Basin region, evaluate natural resources, model wave propagation and improve earthquake locations, among others

Arrival angles of teleseismic fundamental mode Rayleigh waves across the AlpArray

The dense AlpArray network allows studying seismic wave propagation with high spatial resolution. Here we introduce an array approach to measure arrival angles of teleseismic Rayleigh waves. The approach combines the advantages of phase correlation as in the two-station method with array beamforming to obtain the phase-velocity vector. 20 earthquakes from the first two years of the AlpArray project are selected, and spatial patterns of arrival-angle deviations across the AlpArray are shown in maps, depending on period and earthquake location. The cause of these intriguing spatial patterns is discussed. A simple wave-propagation modelling example using an isolated anomaly and a Gaussian beam solution suggests that much of the complexity can be explained as a result of wave interference after passing a structural anomaly along the wave paths. This indicates that arrival-angle information constitutes useful additional information on the Earth structure, beyond what is currently used in inversions

Shear-wave velocity structure beneath the Dinarides from the inversion of Rayleigh-wave dispersion

Highlights • Rayleigh-wave phase velocity in the wider Dinarides region using the two-station method. • Uppermost mantle shear-wave velocity model of the Dinarides-Adriatic Sea region. • Velocity model reveals a robust high-velocity anomaly present under the whole Dinarides. • High-velocity anomaly reaches depth of 160 km in the northern Dinarides to more than 200 km under southern Dinarides. • New structural model incorporating delamination as one of the processes controlling the continental collision in the Dinarides. The interaction between the Adriatic microplate (Adria) and Eurasia is the main driving factor in the central Mediterranean tectonics. Their interplay has shaped the geodynamics of the whole region and formed several mountain belts including Alps, Dinarides and Apennines. Among these, Dinarides are the least investigated and little is known about the underlying geodynamic processes. There are numerous open questions about the current state of interaction between Adria and Eurasia under the Dinaric domain. One of the most interesting is the nature of lithospheric underthrusting of Adriatic plate, e.g. length of the slab or varying slab disposition along the orogen. Previous investigations have found a low-velocity zone in the uppermost mantle under the northern-central Dinarides which was interpreted as a slab gap. Conversely, several newer studies have indicated the presence of the continuous slab under the Dinarides with no trace of the low velocity zone. Thus, to investigate the Dinaric mantle structure further, we use regional-to-teleseismic surface-wave records from 98 seismic stations in the wider Dinarides region to create a 3D shear-wave velocity model. More precisely, a two-station method is used to extract Rayleigh-wave phase velocity while tomography and 1D inversion of the phase velocity are employed to map the depth dependent shear-wave velocity. Resulting velocity model reveals a robust high-velocity anomaly present under the whole Dinarides, reaching the depths of 160 km in the north to more than 200 km under southern Dinarides. These results do not agree with most of the previous investigations and show continuous underthrusting of the Adriatic lithosphere under Europe along the whole Dinaric region. The geometry of the down-going slab varies from the deeper slab in the north and south to the shallower underthrusting in the center. On-top of both north and south slabs there is a low-velocity wedge indicating lithospheric delamination which could explain the 200 km deep high-velocity body existing under the southern Dinarides

Crustal Thinning From Orogen to Back-Arc Basin: The Structure of the Pannonian Basin Region Revealed by P-to-S Converted Seismic Waves

We present the results of P-to-S receiver function analysis to improve the 3D image of the sedimentary layer, the upper crust, and lower crust in the Pannonian Basin area. The Pannonian Basin hosts deep sedimentary depocentres superimposed on a complex basement structure and it is surrounded by mountain belts. We processed waveforms from 221 three-component broadband seismological stations. As a result of the dense station coverage, we were able to achieve so far unprecedented spatial resolution in determining the velocity structure of the crust. We applied a three-fold quality control process; the first two being applied to the observed waveforms and the third to the calculated radial receiver functions. This work is the first comprehensive receiver function study of the entire region. To prepare the inversions, we performed station-wise H-Vp/Vs grid search, as well as Common Conversion Point migration. Our main focus was then the S-wave velocity structure of the area, which we determined by the Neighborhood Algorithm inversion method at each station, where data were sub-divided into back-azimuthal bundles based on similar Ps delay times. The 1D, nonlinear inversions provided the depth of the discontinuities, shear-wave velocities and Vp/Vs ratios of each layer per bundle, and we calculated uncertainty values for each of these parameters. We then developed a 3D interpolation method based on natural neighbor interpolation to obtain the 3D crustal structure from the local inversion results. We present the sedimentary thickness map, the first Conrad depth map and an improved, detailed Moho map, as well as the first upper and lower crustal thickness maps obtained from receiver function analysis. The velocity jump across the Conrad discontinuity is estimated at less than 0.2 km/s over most of the investigated area. We also compare the new Moho map from our approach to simple grid search results and prior knowledge from other techniques. Our Moho depth map presents local variations in the investigated area: the crust-mantle boundary is at 20–26 km beneath the sedimentary basins, while it is situated deeper below the Apuseni Mountains, Transdanubian and North Hungarian Ranges (28–33 km), and it is the deepest beneath the Eastern Alps and the Southern Carpathians (40–45 km). These values reflect well the Neogene evolution of the region, such as crustal thinning of the Pannonian Basin and orogenic thickening in the neighboring mountain belts

Internetbasierte Messungen mit visuellen Analogskalen: Eine experimentelle Untersuchung

The primary concern of the dissertation at hand is to help fill the considerable gap of knowledge regarding Web-based visual analogue (or analog) scales (VASs). VASs are a particular type of rating scales that were described as early as the 1920's (Hayes & Patterson, 1921). Most studies presented here (see Chapters 2, 3, and 4) deal with the influence of VASs on data quality in Web surveys. With VASs, respondent indicate the extent of agreement to an item on a continuum - represented by a straight line - rather than using discrete response categories. The studies presented here were conducted to test if the general restraint in using VASs outside the medical sector - despite the theoretical advantages presented above - is justified or not. The results are meant to facilitate decision-making on the pros and cons of the use of VASs in computer-assisted studies. The potential of graphical response scales focusing on VASs is analyzed in five chapters. Overall, the studies presented in this thesis provide further evidence that rating scales may have a major effect on Web-based data collection. It has to be said, however, that they affect only certain parts of the measurement process - especially question understanding and the formatting process (see Schwarz & Oyserman, 2001; Groves et al. 2009). Although an inappropriate rating scale can considerably harm the quality of a study carefully designed in all other respects, a matching rating scale cannot compensate for flaws in other areas (e.g., poor question wording or graphical design). To assure high-quality data, each and every factor of questionnaire design has to be considered. In practice, there is not one perfect rating scale for each and every questionnaire. The topic of the study, the characteristics of the respondent, the research question, as well as technology have to be taken into account. Especially the study on slider scales presented in Chapter 5 illustrates how the careless use of technology can have a highly negative impact on data collection. On the other hand, the studies on VASs presented in Chapters 2 to 4 serve as an example of how rating scales that differ from commonly used categorical rating scales may have beneficial effects. Overall, it has been demonstrated that VASs provide an important addition to established online research methods. The dissertation at hand has an epistemological and an ethical dimension. All chapters revolve around the question of how rating scales influence knowledge acquisition. By influencing the amount of data noise, rating scales also affect the chance to observe small but important effects. The studies on VASs provide evidence that the reduction of measurement error is not only theoretical; there is also empirical evidence for this important quality of the rating scale. Thus, Web-based measurement with VASs contributes to a broadening of knowledge. To a large extent, psychological research depends on the cooperation of participants. Research ethics imply that the number of participants should be as low as possible. Thus, rating scales are to be preferred that allow a reduction of the needed sample size. Chapter 3 states that the reduction of measurement error with VASs can help achieve statistically significant results with fewer respondents. The resulting reduction of study costs is a positive side effect. Following a paradigm of good scientific practice, the use of VASs should be considered (e.g., made with the free Web service http://vasgenerator, maintained by the author). The methodological studies presented here contribute to a better understanding of how research can profit from VASs. Overall, VASs can significantly improve the measurement of mentally well-represented, continuous latent constructs. Takings the presented findings into account, the reluctance to use VASs in psychological research lacks empirical foundation, at least in Web-based studies. It is therefore recommended that researcher interested in high data quality take advantage of the considerable potential of visual analogue scales.Die Möglichkeiten psychologischer Forschung lassen sich durch die Nutzung des Internets beträchtlich erweitern, sowohl quantitativ - durch den weltweiten Zugriff auf potentielle Untersuchungsteilnehmer -, als auch qualitativ - durch die Erhöhung externer Validität als Folge größerer Varianz von Testsettings. Eine Besonderheit computergestützter Forschung ist, dass sich auch Antwortskalen nutzen lassen, deren Anwendung in gedruckten Fragebögen nicht oder nur unter großem Aufwand möglich ist. Ein Beispiel hierfür sind visuelle Analogskalen (VAS), graphische Messinstrumente in der Form einer horizontalen Linie, deren Enden mit meist verbalen Ankern (z. B. keine Zustimmung versus völlige Zustimmung) versehen sind. Dieser Skalentyp erlaubt Untersuchungsteilnehmern, Antworten auf einem Kontinuum abzugeben. Mit VAS erhobene Daten zeichnen sich neben der Möglichkeit, bereits geringste Unterschiede oder Veränderungen messen zu können, auch durch eine äußerst große Anzahl von Analysemöglichkeiten aus. Trotz aller (mess-)theoretischen Vorteile von VAS gab es bisher kaum methodologische Untersuchungen dieser Antwortskala. Die im Rahmen dieser Dissertation durchgeführten Forschungsarbeiten tragen dazu bei, diese Lücke zu schließen. In mehreren unabhängigen Studien wurde der Einfluss von VAS auf Datenerhebungen im Internet untersucht. In fünf Kapiteln wird das Potenzial graphischer Antwortskalen - vor allem von VAS - untersucht. In Kapitel 1 (Funke & Reips, 2007) werden die Grundlagen und Möglichkeiten von Messungen im Web dargestellt. Anhand relevanter Befunde aus der umfragemethodologischen Literatur wird aufgezeigt, welchen Einfluss unterschiedliche Antwortskalen (u. a. Kategorialskalen, VAS und Sliderskalen) auf die gegebenen Antworten haben können. In Kapitel 2 wird der VAS Generator (http://vasgenerator.net) vorgestellt, mit dem sich online kostenfrei VAS erstellen lassen. In Übereinstimmung mit den theoretischen Annahmen ihrer Messeigenschaften wird gezeigt, dass mit VAS erhobene Daten als intervallskaliert behandelt werden können. In Kapitel 3 wird zunächst eine Simulationsstudie dargestellt, die den Einfluss der Anzahl der Antwortmöglichkeiten bei Kategorialskalen auf den Messfehler untersucht. In zwei empirischen Folgeuntersuchungen wird wie vorhergesagt beobachtet, dass VAS das Rauschen in den Daten verringern und einen praktisch bedeutsamen positiven Effekt auf die Datengüte haben. Kapitel 4 hat eine Untersuchung zum Thema, die zeigt, dass sich Messungen mit semantischen Differentiale durch die Nutzung von VAS optimieren lassen. Zum Abschluss werden in Kapitel 5 schwerpunktmäßig Sliderskalen untersucht. Dabei handelt es sich um einen Skalentyp, der VAS zwar äußerlich ähnelt (zur Abgrenzung siehe Kapitel 1), sich aber in wichtigen Charakteristika - wie Datenqualität und Art der Nutzung - substantiell von ihnen unterscheidet. Sliderskalen erwiesen sich in dem vorgestellten Webexperiment als ein problematisches Messinstrument, da vor allem Untersuchungsteilnehmer mit einer geringen formalen Bildung verstärkt Probleme mit deren Nutzung haben. Die vorliegende Dissertation hat eine erkenntnistheoretische und eine ethische Dimension. Zum einen steht in allen Kapiteln mehr oder weniger explizit die Frage zur Disposition, welchen Einfluss die verwendete Antwortskala auf den Erkenntnisgewinn hat. Um kleine - trotz ihrer geringen absoluten Größe inhaltlich bedeutsame - Unterschiede messen zu können, muss das Fehlerrauschen in den Daten so weit wie möglich verringert werden. Die Untersuchungen zu VAS haben gezeigt, dass die Verringerung des Messfehlers nicht nur eine theoretische Eigenschaft der Skala ist, sondern auch eine empirische Entsprechung hat. Somit ist der Einsatz von VAS in der Onlineforschung dem Erkenntnisgewinn zuträglich. Psychologische Forschung hängt zu einem großen Teil von der Kooperation der Untersuchungsteilnehmer ab. Es sollte nicht nur aus ökonomischem Kalkül Gewicht auf eine möglichst geringe Teilnehmerzahl gelegt werden. Ein Aspekt ethisch verantwortungsvollen Forschens besteht darin, der Antwortskala Vorzug zu geben, die die benötigte Teilnehmerzahl verringert. Wie die in Kapitel 3 beschriebene Reduzierung des Messfehlers zeigt, können VAS dazu einen Betrag leisten und sollten somit auch unter dem Gesichtspunkt guter wissenschaftlicher Praxis genutzt werden. Insgesamt sind die hier vorgestellten methodologischen Untersuchungen außerordentlich vielversprechend. VAS können Messungen mental gut repräsentierter, kontinuierlicher latenter Variablen deutlich verbessern. Die kaum verbreitete Nutzung von VAS in der psychologischen Forschung entbehrt nach den hier gewonnenen Erkenntnissen zumindest bei Untersuchungen im Internet jeglicher Grundlage. An hoher Datenqualität interessierte Forscher sollten das Potenzial visueller Analogskalen für ihre webbasierten Studien ausschöpfen

Sliders, visual analogue scales, or buttons : Influence of formats and scales in mobile and desktop surveys

In an experiment dealing with the use of personal computer, tablet, or mobile, scale points (up to 5, 7, or 11) and response formats (bars or buttons) are varied to examine differences in mean scores and nonresponse. The total number of “not applicable” answers does not vary significantly. Personal computer has the lowest item nonresponse, followed by mobile and tablet, and a lower mean score than for mobile. Slider bars showed lower mean scores and more nonresponses than buttons, indicating that they are more prone to bias and difficult in use. Sider bars, which work with a drag-and-drop principle, perform worse than visual analogue scales working with a point-and-click principle and buttons. Five-point scales have more nonresponses than eleven-point scales. Respondents evaluate 11-point scales more positively than shorter scales

ASC 2007. THE CHALLENGES OF A CHANGING WORLD Edited by M. Trotman et al Compilation © 2007 Association for Survey Computing Video Web Survey- Results of an experimental comparison with a text-based Web survey

Since the early days of Web surveying it was recognized as a potential advantage of computer mediated surveying to enrich studies with multimedia stimuli such as graphics, pictures, spoken word or other sounds. But in fact, these possibilities have only seldom put into action. Just in recent years Web surveys have been enriched by graphics and pictures – some of which are content bearing. Methodological evaluations have shown that these pictures can have a serious impact on the perceived question meaning and thus on the responses provided. In this paper we will report preliminary results from an assessment of the next step towards a full audiovisual Web survey. In spring of 2007 we have conducted a field experimental randomized comparison of a traditional text-based Web surveys to a Web survey containing videos of an interviewer reading the questions to the respondents. In the paper, unit nonresponse, social desirability and social presence are evaluated. In addition, we assess response times as well as the social setting and the location in which the survey was filled in. Finally we will consider ideas on how the underlying question answer process can be examined in greater detail