Purpose -The aim of this paper is to present a sampling method using virtual networks to study "hard-to-reach" populations. In the ambit of social research, the use of new technologies is still questioned because the selection bias is an obstacle to carry on scientific research on the Internet. In this regard, the authors' hypothesis is that the use of social networking sites (Web 2.0) can be effective for the study of "hard-to-reach" populations. The main advantages of this technique are that it can expand the geographical scope and facilitates the identification of individuals with barriers to access. Therefore, the use of virtual networks in non-probabilistic samples can increase the sample size and its representativeness. Design/methodology/approach -To test this hypothesis, a virtual method was designed using Facebook to identify Argentinean immigrant entrepreneurs in Spain (214 cases). A characteristic of this population is that some individuals are administratively invisible in national statistics because they have double nationality (non-EU and EU). The use of virtual sampling was combined with an online questionnaire as a complementary tool for Web 2.0 research in behavioural sciences. Findings -The number of cases detected by Facebook and the virtual response rate is higher than traditional snowball technique. The explanation is that people increase their level of confidence because the researcher shows his personal information (Facebook's profile) and also participates in their groups of interest (Facebook's groups). Moreover, the online questionnaires administration allows the quality of the information to be controlled and avoids duplication of cases. Originality/value -The present article is the first that uses Facebook as an instrument to study immigrants. Therefore its adoption represents a great challenge in the social research field because there are many barriers of access and search. It also proposes a novel mix of traditional methodologies updated with the use of new virtual possibilities of studying hard to reach populations, especially in areas of social research where the contributions of these methods are less developed.

The aim of this article is to analyse the factors affecting the motivations of immigrant entrepreneurs to generate an entrepreneurial gain (positive impact on home and host countries). We consider that positive reasons for emigrating can increase transnational entrepreneurship and mutual benefits for both societies. To test this hypothesis we present a model using Structural Equation Modelling (SEM).This model explains the relations between motivations, cultural similarities, institutions and transnational linkage potentials. We designed an ad hoc search of Argentinean entrepreneurs established in Spain, both as EU citizens and without legal EU status, using online social networks. We applied an online questionnaire to 214 such entrepreneurs. We conclude that institutional rules (formal and informal) greatly influence the location decisions of firms and immigrant entrepreneurs' motivations for starting transnational business because they provide the frame for the development of profitable opportunities.

ResumenObjeto: El objetivo de este artículo es explorar las posibilidades que ofrecen las nuevas tecnologías de información y la aparición de las redes sociales virtuales, para el reclutamiento de unidades muestrales en poblaciones ocultas y como soporte del uso de métodos mixtos.Diseño/metodología/enfoque: El objetivo era identificar a los empresarios argentinos que iniciaron negocios en España. Esta unidad de observación, presenta características que la definen como población oculta: 1) elevada dispersión geográfica que dificulta su localización; 2) subestimación en el número de argentinos residentes en las estadísticas oficiales; 3) argentinos residentes en situación ilegal; y, 4) en muchos casos los factores que motivaron la emigración son negativos, por lo que genera reticencia a contestar.En este contexto, se desarrolló (1) el muestreo virtual online y (2) el muestreo por bola de nieve tradicional. En el muestreo virtual online se utilizó la red social Facebook, mediante la cual se identificaron 52 grupos virtuales que nuclean a argentinos que viven en España. Posteriormente, se envío a cada miembro un mensaje personal explicando el propósito del estudio e invitándolos a participar en el mismo.Aportaciones y resultados: A través de la realización del estudio, se comprueba que mediante el uso de redes sociales es posible acceder a unidades de observación que no se hubieran detectado por vías

Practical issues associated with sampling and data collection are of real concern to business researchers. Some important methodological issues are the willingness to participate of the individuals and the provision of accurate information. Therefore, the aim of this article is to present the results obtained from the combination of social networking sites (Facebook) with an online questionnaire to study transnational entrepreneurs in Spain. The article analyses the pattern of answer of 219 entrepreneurs surveyed, and a cluster analysis of respondents and types of question is developed. The conclusion is that new technologies can help researchers to tackle some of the limitations associated with the administration of surveys to business people (e.g. lack of motivation to answer, intermediate filters) and can improve the quality of the information collected (e.g. higher level of response to confidential questions). However, it is acknowledged that ethical and methodological considerations are of great importance in this kind of study.

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