Daniele Toninelli

Set-Portfolio Selection with the Use of Market Stochastic Bounds

This paper proposes an ex post comparison of portfolio selection strategies. These strategies are applied to a set of assets, preselected among about 10,000 stocks on the global market. The preselection criteria consider the joint Markovian behavior of the returns and their association with the market stochastic bounds. Furthermore, we examine the performance and the impact of different strategies that use or do not use the preselection criteria. Finally, we compare the ex post wealth obtained with the optimization of several reward-risk performance functionals that use the stochastic bounds of the preselected assets.

Do online access panels need to adapt surveys for mobile devices

Purpose n n n n nDespite the quick spread of the use of mobile devices in survey participation, there is still little knowledge about the potentialities and challenges that arise from this increase. The purpose of this paper is to study how respondents’ preferences drive their choice of a certain device when participating in surveys. Furthermore, this paper evaluates the tolerance of participants when specifically asked to use mobile devices and carry out other specific tasks, such as taking photographs. n n n n nDesign/methodology/approach n n n n nData were collected by surveys in Spain, Portugal and Latin America by Netquest, an online fieldwork company. n n n n nFindings n n n n nNetquest panellists still mainly preferred to participate in surveys using personal computers. Nevertheless, the use of tablets and smartphones in surveys showed an increasing trend; more panellists would prefer mobile devices, if the questionnaires were adapted to them. Most respondents were not opposed to the idea of participating in tasks such as taking photographs or sharing GPS information. n n n n nResearch limitations/implications n n n n nThe research concerns an opt-in online panel that covers a specific area. For probability-based panels and other areas the findings may be different. n n n n nPractical implications n n n n nThe findings show that online access panels need to adapt their surveys to mobile devices to satisfy the increasing demand from respondents. This will also allow new, and potentially very interesting data collection methods. n n n n nOriginality/value n n n n nThis study contributes to survey methodology with updated findings focusing on a currently underexplored area. Furthermore, it provides commercial online panels with useful information to determine their future strategies.

An experiment comparing grids and item-by-item formats in web surveys completed through PCs and smartphones

The device used to answer web surveys should be taken into account.Similar levels of interitem correlations are found in PCs and smartphones.Longer completion times are found for grid questions for smartphone respondents.Sometimes less non-differentiation is observed for PCs.Using item-by-item format for all devices is a way to improve comparability. Some respondents already complete web surveys via mobile devices. These devices vary at several levels from PCs. In particular, we expect differences when grid questions are used due to the lower visibility on mobile devices and because in questionnaires optimized to be completed through smartphones, grids are split up into an item-by-item format.This paper reports the results of a two-wave experiment conducted in Spain in 2015, comparing three groups: PCs, smartphones not-optimized, or smartphones optimized.We found similar levels of interitem correlations, longer completion times for grid questions for smartphone respondents, and sometimes less non-differentiation for PCs. Thus, using the item-by-item format for smartphones and PCs seems the most appropriate way to improve comparability.