On the selection of AGN neutrino source candidates for a source stacking analysis with neutrino telescopes

The sensitivity of a search for sources of TeV neutrinos can be improved by grouping potential sources together into generic classes in a procedure that is known as source stacking. In this paper, we define catalogs of Active Galactic Nuclei (AGN) and use them to perform a source stacking analysis. The grouping of AGN into classes is done in two steps: first, AGN classes are defined, then, sources to be stacked are selected assuming that a potential neutrino flux is linearly correlated with the photon luminosity in a certain energy band (radio, IR, optical, keV, GeV, TeV). Lacking any secure detailed knowledge on neutrino production in AGN, this correlation is motivated by hadronic AGN models, as briefly reviewed in this paper. The source stacking search for neutrinos from generic AGN classes is illustrated using the data collected by the AMANDA-II high energy neutrino detector during the year 2000. No significant excess for any of the suggested groups was found.Comment: 43 pages, 12 figures, accepted by Astroparticle Physic

Survey context effects and implications for validity: Measuring political discussion frequency in survey research

Although political discussion behavior is an important area of political communication research, analysis of the reliability and validity of political discussion survey measures has only recently begun. This study uses panel survey data to examine the effects of survey context on self-reported political discussion frequency measures (e.g., general political discussion, discussion about the economy), the moderating influence of individual difference variables, and implications for measurement validity. A quasi-experiment demonstrates that including a large (versus small) quantity of preceding issue-relevant questions leads to higher reports of political and economic discussion frequency, and this effect is greater for individuals with higher levels of political and economic interest, respectively. Results of a survey experiment reveal that inclusion of a preceding thought-listing question about the economy produces higher reports of economic talk frequency, but only among those who possess relatively expansive conceptualizations of the economy. Such survey context effects suggest problems with the construct validity of self-reported political discussion frequency measurements. Potential consequences of survey context for concurrent and predictive validity are assessed by examining relationships between discussion frequency and known correlates (e.g., education, interest) and outcomes (e.g., current affairs knowledge) of political talk. Results provide tentative evidence that discussion measures placed after a large (versus small) quantity of issue-relevant questions may exhibit better criterion validity (quasi-experiment), whereas the order of a thought-listing question does not appear to impact criterion validity (experiment). Results of this study clearly underscore the need for additional research on self-report measures of political behavior, including political discussion frequency

Political talk preferences: Selection of similar and different discussion partners and groups

Focusing on two distinct dimensions of similarity and difference (political identity, political opinions), this study uses a within-subjects experimental design implemented in an online survey to examine preferences for discussion partners and groups that are similar to (same party and same opinion) or different from (different party and different opinion) or that represent a combination of similarity and difference (same party and different opinion, or different party and same opinion) relative to oneself. Participants comprising a diverse national sample (N = 820) completed eight political discussion selection tasks (four discussion partner tasks, four discussion group tasks) by ranking four political discussion options from most to least preferred. Results indicate that complete similarity is not always preferred (in analyses of all ranked discussion groups) and that partisan similarity is preferred over opinion similarity (in analyses of first-ranked discussion partners). More generally, findings reveal that preferences for political discussion depend on the context of the discussion, including whether the discussion involves a single discussion partner or a discussion group and whether preference focuses on individuals’ most preferred option only or relative rankings across a range of options