Showing papers in "American Sociological Review in 1996"

The Sources and Consequences of Embeddedness for the Economic Performance of Organizations: The Network Effect

Abstract: L'A s'efforce de comprendre comment les structures sociales influent sur la performance economique Il s'interesse plus particulierement a la notion d'« enracinement » Il montre que celle-ci permet de saisir comment les relations sociales modelent l'activite economique Il porte de meme son attention sur les reseaux sociaux qui jouent un role important en cette affaire Il examine en premier lieu le concept d'enracinement structurel Il compare ensuite les performances economiques d'entreprises americaines qui fonctionnent en reseaux avec les resultats d'activite d'entreprises qui n'operent que par le biais du marche Il presente, a ce propos, un certain nombre de donnees collectees aux Etats-Unis, a New York entre 1990 et 1991

Changing highbrow taste: from snob to omnivore*

Abstract: Appreciation of fine arts became a mark of high status in the late nineteenth century as part of an attempt to distinguish highbrowed Anglo Saxons from the new lowbrowed immigrants, whose popular entertainments were said to corrupt morals and thus were to be shunned (Levine 1988; DiMaggio 1991). In recent years, however, many high-status persons are far from being snobs and are eclectic, even omnivorous, in their tastes (Peterson and Simkus 1992). This suggests a qualitative shift in the basis for marking elite status-from snobbish exclusion to omnivorous appropriation. Using comparable 1982 and 1992 surveys, we test for this hypothesized change in tastes. We confirm that highbrows are more omnivorous than others and that they have become increasingly omnivorous over time. Regression analyses reveal that increasing omnivorousness is due both to cohort replacement and to changes over the 1980s among highbrows of all ages. We speculate that this shift from snob to omnivore relates to status-group politics influenced by changes in social structure, values, art-world dynamics, and generational conflict

Markets as Politics: A Political‐Cultural Approach to Market Institutions

Abstract: L'A examine la perspective sociologique qui affirme que la stabilite du marche n'est possible que si les acteurs prennent en compte leurs actions reciproques Il montre que celle-ci s'oppose a la conception neoclassique du fonctionnement du marche qui insiste sur l'anonymat des acteurs Il s'efforce d'elaborer une vision politique du marche qui prenne en compte dans une approche ecologique le role des institutions et celui des reseaux sociaux Il considere que l'on doit envisager les processus qui s'observent au niveau du marche comme refletant les luttes internes au sein de l'entreprise et la competition entre chacune d'elles

Perceptions of racial group competition: Extending Blumer's theory of group position to a multiracial social context

Abstract: Perceptions of threat occupy a central place in race relations in Blumer's theory of prejudice but few direct efforts to study such perceptions exist. Extending Blumer's reasoning, we hypothesize that such perceptions are driven by a group's feelings of racial alienation within the larger social order The more that members of a particular racial group feel collectively oppressed and unfairly treated by society, the more likely they are to perceive members of other groups as potential threats. We also examine whether such perceptions spring from simple self-interest, orthodox prejudice such as negative feelings and stereotyping, or broad beliefs about social stratification and inequality. We use data from the 1992 Los Angeles County Social Survey, a large multiracial sample of the general population, to analyze the distribution and social and psychological underpinnings of perceived group competition. Our results support the racial alienation hypothesis as well as the hypotheses positing effects for self-interest, prejudice, and stratification beliefs. We argue that Blumer's group-position framework offers the most parsimonious integration and interpretation of the social psychological processes involved in the formation of perceptions of group threat and competition. O ) ngoing immigration from Asia and Latin America and the earlier internal migration of African Americans out of the rural South have made most large cities in the United States remarkable multiracial conglomerations (Waldinger 1989). An immediate sociological concern raised by the growing heterogeneity of urban areas is whether members of different groups view one another as direct competitors for scarce economic, political, and social resources (Olzak 1993). Such perceptions may influ

Routine Activities and Individual Deviant Behavior

Abstract: We extend the routine activity perspective's situational analysis of crime to individual offending and to a broad range of deviant behaviors. In this view, unstructured socializing with peers in the absence of authority figures presents opportunities for deviance: In the presence of peers, deviant acts will be easier and more rewarding; the absence of authority figures reduces the potential for social control responses to deviance; and the lack of structure leaves time available for deviant behavior. To determine whether individuals who spend more time in unstructured socializing activities engage in deviant behaviors more frequently, we analyzed within-individual changes in routine activities and deviance across five waves of data for a national sample of more than 1,700 18- to 26-year-olds. Participation in these routine activities was strongly associated with criminal behavior, heavy alcohol use, use of marijuana and other illicit drugs, and dangerous driving. Furthermore, routine activities accounted for a substantial portion of the association between these deviant behaviors and age, sex, and socioeconomic status.

Anything but heavy metal : Symbolic exclusion and musical dislikes

Abstract: The author provides quantitative evidence of a cultural phenomenon. Using data on musical dislikes from the 1993 General Social Survey, He links literatures on taste, racism, and democratic liberalism by showing that people use cultural taste to reinforce symbolic boundaries between themselves and categories of people they dislike. Contrary to Bourdieu's (1984) prediction, musical exclusiveness decreases with education. Also, political tolerance is associated with musical tolerance, even controlling for educational attainment, and racism increases the probability of disliking genres whose fans are disproportionately non-White. Tolerant musical taste, however, is found to have a specific pattern of exclusiveness : Those genres whose fans have the least education-gospel, country, rap, and heavy metal-are also those most likely to be rejected by the musically tolerant. Broad familiarity with music genres is also significantly related to education. He suggests, therefore, that cultural tolerance constitutes multicultural capital as it is unevenly distributed in the population and evidences class-based exclusion

Immigrant Self-Employment: The Family as Social Capital and the Value of Human Capital

Abstract: We examine how self-employment among Asian and Hispanic immigrants is affected by family composition and human capital/class resources. Because of collective interests and strong personal ties the family facilitates the pooling of labor power and financial resources. Enterprising immigrants draw on these resources when establishing and operating small businesses. Our findings also show the importance of human capital/class resources in accounting for immigrant self-employment. Although foreign-earned human capital is usually not highly valued in the host labor market immigrants successfully use this human capital to achieve business ownership. Interethnic variation in personal human capital and family composition accounts for a substantial portion of the observed interethnic variation in self-employment....The data are drawn from the 1980 five percent PUMS for greater New York City and Los Angeles.... (EXCERPT)

Commitment in exchange relations: Test of a theory of relational cohesion

Abstract: Les AA. proposent un modele d'evaluation de la theorie de la cohesion relationnelle. Celle-ci permet de predire comment et quand les individus dans le cadre des echanges se sentent engages dans le jeu relationnel. Celle-ci met en avant une conception dyadique de ce type de relation sociale et affirme qu'une situation percue de plus grande egalite de pouvoir stimule des echanges concus positivement et induit une perception de la relation concue comme une unite coherente

Exploring the Limits of the New Institutionalism: The Causes and Consequences of Illegitimate Organizational Change

Abstract: While the new institutionalism has emerged as a dominant theory of organization-environment relations, very little research has examined its possible limits. Under what circumstances might the neoinstitutional predictions regarding organizational inertia, institutional isomorphism, the legitimacy imperative, and other fundamental beliefs be overshadowed by more traditional sociological theories accentuating organizational adaptation, variation, and the role of specific global and local technical environmental demands? We analyze longitudinal data from 1971 to 1986 for 631 private liberal arts colleges facing strong institutional and increasingly strong technical environments. Our findings reveal surprisingly little support for neoinstitutional predictions: (1) Many liberal arts colleges changed in ways contrary to institutional demands by professionalizing or vocationalizing their curricula; (2) global and local technical environmental conditions, such as changes in consumers' preferences and local economic and demographic differences, were strong predictors of the changes observed; (3) schools became less, rather than more, homogeneous over time; (4) schools generally did not mimic their most prestigious counterparts; (5) the illegitimate changes had no negative (and often had positive) performance consequences for enrollment and survival. Our results suggest that current research on organization-environment relations may underestimate the power of traditional adaptation-based explanations in organizational sociology

Ending Footbinding and Infibulation: A Convention Account

Abstract: This paper explores the close similarities between Chinese footbinding and female genital mutilation and categorizes each custom as universal where practiced persistent practiced by those opposed to it a way to control sexual access to females considered necessary for proper marriage and family honor sanctioned by tradition an ethnic marker spread by contagious diffusion exaggerated over time related to status supported and transmitted by women performed on young girls generally not initiation rites believed to promote health and fertility considered aesthetically pleasing considered an enhancement to male pleasure during intercourse and related to female slavery. After noting these characteristics the paper defends these assertions by tracing the history of female footbinding in China and defining and tracing the history of female genital mutilation in Africa. The authors conclusion that each practice is a self-enforcing convention (as defined by Shelling in 1960 and Lewis in 1969) is presented through a discussion of the convention hypothesis and game theory illustrated through coordination problems. This theory illustrates how people can be stuck in an inferior equilibrium which is maintained by what people believe about each other (daughters will be forced to undergo genital mutilation if people believe this is necessary to attract a husband). Such a convention is self-enforcing and in these cases the enforcement is derived by a desire for paternity confidence by a history of imperial female slavery and by belief traps. The mechanism necessary to allow escape from an inferior convention is then covered and it is recommended that efforts to end female genital mutilation adopt the successful tactics which eradicated footbinding in China in one generation. Quick convention change can be achieved by an education campaign by use of adverse international public opinion and by forming associations of parents who pledge not to submit their daughters to genital mutilation and not to let their sons marry mutilated women.

Images of protest: Dimensions of selection bias in media coverage of Washington demonstrations, 1982 and 1991

Abstract: Protest is now central to politics in Western democracies, but it is known to citizens mainly through portrayals in the media. Yet the media cover only a small fraction of public protests, raising the possibility of selection bias. We study this problem by comparing police records of demonstrations in Washington, D.C. in 1982 and 1991 with media coverage of the events in The New York Times, The Washington Post, and on three national television networks. We model the consequences of demonstration form, context, and purpose on the likelihood of media coverage. The estimated size of a demonstration and its importance to the current media issue attention cycle are the strongest predictors of its coverage. Additional analyses support our claim that heightened media attention to an issue increases the likelihood that protests related to that issue will be covered. Comparing 1982 to 1991 suggests that television coverage of protests is increasingly subject to the impact of media issue attention cycles.

The effect of social relationships on psychological well-being: Are men and women really so different?

Abstract: We assess evidence for gender differences across a range of relationships and consider whether the form and quality of these relationships affect the psychological functioning of men and women differently. Data from a national panel survey provide consistent evidence that men's and women's relationships differ. However, we find little evidence for the theoretical argument that women are more psychologically reactive than men to the quality of their relationships : Supportive relationships are associated with low levels of psychological distress, while strained relationships are associated with high levels of distress for women and for men. However, if women did not have higher levels of social involvement than men, they would exhibit even higher levels of distress relative to men than they currently do. We find little evidence for the assertion that men and women react to strained relationships in gender-specific ways-for example, with alcohol consumption versus depression

Take the money and run: economic segregation in U.S. metropolitan areas.

Abstract: Compared to residential segregation by race, economic segregation has received relatively little attention in recent empirical literature. Yet a heated debate has arisen concerning Wilson's (1987) hypothesis that increasing economic segregation among African Americans plays a role in the formation of urban ghettos. The author presents a methodological critique of the measure of economic segregation used by Massey and Eggers (1990) and he argues that their measure confounds changes in the income distribution with spatial changes. He develops a pure measure of economic segregation based on the correlation ratio and present findings for all U.S. metropolitan areas from 1970 to 1990. Economic segregation increased steadily for Whites, Blacks, and Hispanics in the 1970s and 1980s, but the increases have been particularly large and widespread for Blacks and Hispanics in the 1980s. The author explores the causes of these changes in a reduced-form, fixed-effects model. Social distance and structural economic transformations affect economic segregation, but the large increases in economic segregation among minorities in the 1980s cannot be explained by the model. These rapid increases in economic segregation, especially in the context of recent, albeit small, declines in racial segregation, have important implications for urban policy, poverty policy, and the stability of urban communities

Market transition and the persistence of power: The changing stratification system in urban China

Abstract: Research on transitional socialist societies has explored trends in income inequality and issues concerning who gains and who loses during market reforms. We find that income inequality in a major Chinese city declined only slightly during the first decade of reform policies; it then increased dramatically in the subsequent five years. Strategic position in the state bureaucracy continues to be an important determinant of income, although connections to the market system are becoming alternate sources of advantage. We interpret these findings in light of the historical and institutional context of urban China

Concessions, repression, and political protest in the Iranian revolution

Abstract: L'A. cherche a comprendre en quoi les differentes politiques tantot de compromis et tantot de repression du Shah, entre 1977 et 1978 ont provoque l'escalade revolutionnaire en Iran. Il montre que la repression a eu un effet negatif a court-terme vis-a-vis de la protestation. Du fait de la repression, celle-ci apparait comme presentant un cout. En revanche sur le long terme, la repression quand elle est jugee illegitime contribue a discrediter le pouvoir en place. L'A. affirme que cette situation ambivalente resulte d'une combinaison d'effets dissuasifs et d'effets stimulant la mobilisation

An interactive model of religiosity inheritance: The importance of family context.

Abstract: I use an intergenerational data set that is uniquely suited to estimating the magnitude of religiosity inheritance. Interviews with 471 parents in 1980 and their adult offspring in 1992 address three related issues: (1) What are the effects of childhood, parental, and family influences on the religiosity of adult offspring ? (2) What factors condition the ability of parents to transmit their religiosity ? (3) How do the recent experiences of adult offspring modify earlier family influences on religiosity ? The results suggest that three sets of variables aid the transmission of religiosity-parental religiosity, quality of the family relationship, and traditional family structure. One's religiosity is determined largely by the religiosity of one's parents. Parent's marital happiness, parent-child support, moderate strictness, and a working husband/ nonworking wife increase the ability of parents to transmit their religious beliefs and practices. Although the recent experiences of adult offspring affect their religiosity, these experiences do not reduce the influence of parents and family context

New kid in town: Social capital and the life course effects of family migration on children

Abstract: Les AA. etudient l'impact des demenagements sur la vie des familles et plus particulierement sur la reussite scolaire des enfants. Ils presentent un certain nombre de donnees collectees a Toronto, au Canada, entre 1976 et 1989. Ils s'efforcent de dresser une typologie des demenagements effectues par les familles et leur frequence. Ils examinent l'influence en ce domaine d'un certain nombre de facteurs comme la structure familiale, le statut socio-economique du pere celui de la mere, l'aide scolaire apportee par chacun d'eux

Keiretsu Networks and Corporate Performance in Japan

Abstract: Les AA. presentent un certain nombre de donnees collectees au Japon entre 1965 et 1988 concernant les grandes entreprises de ce pays et etudient plus particulierement les keiretsu, un type de reseau qui unit de tres nombreuses entreprises japonaises aux six plus importantes : les trois plus grands groupes financiers et les trois plus grands groupes industriels. Ils montrent que ce type d'organisation joue un grand role dans l'economie du pays et examinent les liens de dependance financiers et commerciaux qu'il implique et les consequences que cela induit en ce qui concerne les performances des societes qui lui sont liees

Effects of family instability income and income instability on the risk of a premarital birth.

Abstract: In this study I contrast hypotheses about the effects of family structure on premarital birth risks with three income hypotheses: (1) a low income hypothesis--that the risk of a premarital birth is higher for women from disadvantaged economic backgrounds because they possess fewer or less attractive economic opportunities; (2) a permanent income and transitory income hypothesis--that uncertainties generated by unexpected fluctuations in family income increase premarital birth risks net of absolute income levels; and (3) an income level and income change hypothesis--that downward trends in family income reflect worsening socioeconomic opportunities that increase premarital birth risks net of absolute income levels. I use prospective income and retrospective parental histories in the [U.S.] National Longitudinal Survey of Youth to determine if the effect of family instability...is an artifact of low unstable or declining income in the family of origin. (EXCERPT)

Life after welfare: Women, work, and repeat dependency

Abstract: L'A. montre que les femmes constituent, aux Etats-Unis, la categorie la plus importante parmi les beneficiaires de l'aide sociale. Il souligne que celles-ci ont recours a l'aide sociale principalement en cas de divorce, lorsque survient une naissance premaritale ou une difficulte economique. Il s'efforce de comprendre ce qui conduit les femmes a faire a nouveau appel a ce type d'aide. Il presente des donnees collectees aux Etats-Unis entre 1983 et 1988. Il examine l'influence d'un certain nombre de facteurs comme le statut marital, les experiences de cohabitation, l'âge, le revenu familial, le nombre d'enfants et plus particulierement d'enfants en bas âge

Structural opportunity and perceived opportunity in social-movement theory : the Iranian revolution of 1979

Abstract: Les analyses de Tocqueville des mouvements sociaux apparaissent comme des cas limites ou les chances structurelles (la vulnerabilite de l'Etat a la pression politique populaire) coincide avec les chances percues (le fait que le public soit au courant des possibilites de succes dans le cadre de son activite de protestation). L'A. estime toutefois que cette coincidence n'apparait pas toujours. Il met en avant une disjonction de ce type en ce qui concerne la revolution iranienne entre 1977 et 1979. Sur certains plans la monarchie n'etait pas, en soi, vulnerable sur le plan structurel. Les iraniens ont percu, en revanche, une possibilite de succes en observant un changement dans la nature du mouvement de protestation

Mobilization at the margins: resources, benefactors, and the viability of homeless social movement organizations*

Abstract: For over two decades, resources have been assumed to be a fundamental determinant of the course and character of social movement organizations (SMOs) and their activities. Yet surprisingly little research evaluates this taken-for-granted assumption. Using data from ethnographic fieldwork on 15 homeless SMOs in eight U.S. cities, we construct an empirically grounded typology of resources and assess the combinations of resources necessary for the viability of homeless SMOs. We then examine the sources of support for these organizations, highlighting the influence of benefactor organizations on SMO viability and tactics. Employing qualitative comparative analysis, we identify three resource configurations among the viable SMOs and find that certain resource types contributed more than others to viability. Support from benefactors also ensured viability of these organizations without moderating their tactics. We explain the implications of these findings for understanding the roles that resources and sponsorship or patronage play in the careers of SMOs and the relevance of resources, sponsorship, and organization to social movements of the poor. early two decades after the flowering of the resource mobilization perspective on social movements, many of the perspective's assumptions have been "assimilated as the routine and unstated grounds of much contemporary work" (Zald 1992:327). One such taken-for-granted assumption is that resources are a sine qua non determinant of the course and character of social movement organizations (SMOs) and their activities. Indeed, no other assumption is so fundamental to the resource mobilization perspective and a plethora of derivative work. Yet there is little definitive understanding of several resource-related issues relevant to the dynamics of SMOs. One such issue concerns the conceptualization and identification of resources; a second issue addresses whether some types of resources are more important than others for mobilization and collective action; the third issue concerns resource derivation, particularly the relative importance of externally derived versus internally derived resources; and the fourth issue concerns the implications of external support for SMO viability and tactical actions. We address these four issues with data on 15 homeless SMOs in eight U.S. cities, and we explore the implications of our findings for a more nuanced understanding of social movements of the poor.

Socioeconomic Achievement in the Life Course of Disadvantaged Men: Military Service as a Turning Point, Circa 1940-1965

Abstract: Les AA. s'efforcent de comprendre en quoi le service militaire, particulierement en temps de guerre, peut affecter la vie socio-professionnelle d'un individu. Ils presentent un certain nombre de donnees collectees, aux Etats-Unis, entre 1940 et 1965 concernant de jeunes adultes issus de milieux defavorises dont un grand nombre de delinquants et qui ont fait leur service pendant la Deuxieme Guerre mondiale. Ils examinent l'influence de l'experience militaire sur la reussite socio-professionnelle ulterieure

The dynamics and dilemmas of collective action

Abstract: Theoretical accounts of participation in collective action have become more divergent. Some analysts employ the Prisoner's Dilemma paradigm, other analysts suggest that different social dilemmas underlie collective action, and still others deny that social dilemmas play any significant role in collective action. I propose a theoretically exhaustive inventory of the dilemmas arising in collective action systems and show thatfive games, including the Prisoner's Dilemma, can underlie collective action. To analyze action within each game I use a dynamic selectionist model based on three modes of organization-voluntary cooperation, strategic interaction, and selective incentives. Social dilemmas exist in four of the five games, and conflicting accounts of collective action have focused on different games and modes of organization. As collective action proceeds from initiation to rapid expansion to stability, its game type varies in a way that can be precisely characterized as movement through a two-dimensional game-space. Finally, I distinguish between two ways of promoting collective action: One way focuses on resolving the dilemma within a particular game; the other focuses on changing the game so the dilemma is more easily resolved or eliminated.

A re-evaluation of the economic consequences of divorce.

Abstract: Over the last 20 years researchers have focused considerable attention on the economic consequences of divorce. One book Weitzmans The Divorce Revolution (1985) reports a 73 percent decline in womens standard of living after divorce and a 42 percent increase in mens standard of living. These percentages based on data from a 1977-1978 Los Angeles sample are substantially larger than those from other studies. I replicate...[this] analysis and demonstrate that the estimates reported in the book are inaccurate. This reanalysis...produces estimates of a 27 percent decline in womens standard of living and a 10 percent increase in mens after divorce. I discuss the implications of these results for debates about divorce law reform. (EXCERPT)

Self-Employment and the Earnings of Immigrants

Abstract: We examine the question of the economic returns to immigrants engaged in self-employment....Based on samples of four entrepreneurial immigrants plus control samples of Blacks and Whites from the 1980 [U.S.] Public Use Microdata Sample we find large differences in the net effect of self-employment depending on the use of a linear (absolute dollar values) or loglinear (relative returns) form. We examine various explanations for the discrepancy and identify the role of outliers as significant. The loglinear form fits the data better but at the cost of obliterating substantively important information namely the preponderance of the self-employed among positive outliers. Effects of excluding the latter from the linear form and the theoretical and policy implications of alternative specifications of the earnings equation are examined. (EXCERPT)

Linking mobilization frames and political opportunities : Insights from regional populism in Italy

Abstract: Drawing on the case of the Northern League in Italy, I provide a framework for systematically relating insights from two major currents of recent research on collective action: framing processes and political opportunity structures. Cross-classifying two variables-the stability of political alignments and the opportunities for autonomous action within the polity-yields four types of political structures; each is particularly conducive to different "master frames" (antisystem, inclusion, revitalization, and realignment). This approach also improves specification of the role of organizational resources. These resources become substantially more effective if the strategies they are supposed to support are framed in a way consistent with the masterframe and the opportunity structure. T he regionalist parties that form the Northern League' have played a major role in recent Italian politics. Their impressive electoral growth between 1990 and 1993 has undermined support for traditional parties, including oppositional parties, and has paved the way for the advent of Mr. Berlusconi's party, Forza Italia. In this paper I do not discuss the events that have followed

Testing a dynamic model of social composition: diversity and change in voluntary groups*

Abstract: We test a dynamic model of the social composition of voluntary groups. The model is based on the idea that sociodemographic variables define social niches in which voluntary groups grow and decline, share and compete, and change or remain static. The flow of individuals through such groups depends on the competition of other groups for their time and other resources. We build a dynamic model of this process and show how this model can account for changes in the social composition and the social heterogeneity of voluntary groups. We use life history data on the group affiliations of 1,050 individuals from 1974 to 1989 to test hypotheses about the diversity of education among group members and about the mean level of education of the members. Our data strongly support the hypotheses.

Memory as a cultural system : Abraham Lincoln in World War II

Abstract: Studies of how societies preserve the past have focused on the social frames of memory. This study of Abraham Lincoln during World War II extends a semiotic interpretation of culture as it focuses on memory as a social frame. Memories invoked in the context of a present crisis are rooted in generational experience. One-third of all Americans living in 1940 were born during the late nineteenth century, when Civil War resentments were fading and remembrances of Lincoln were more positive and vivid than ever. This generation understood the meaning of World War II by keying it to the Civil War. Patterned arrays of images of Lincoln were invoked by local and federal agencies to clarify the purpose of World War II, legitimate the preparations for it, and then to orient, inspire, and console the people who fought it. As a model for the present and of the present, images of Lincoln comprised a cultural system that rationalized the experience of war. I compare and contrast memory as a cultural system with constructionist theories of collective memory and discuss it in light of the erosion of American society's grand narratives

Is bigger better? Explaining the relationship between organization size and job rewards

Abstract: Les AA. s'efforcent de savoir si les employes des grandes organisations recoivent du point de vue de leur travail plus de recompenses economiques et non-economiques que ceux des organisations de taille plus modeste. Ils cherchent de meme a identifier quelle peut etre la nature de ce lien entre taille d'organisation et gratification professionnelle. Dans ce but ils presentent et etudient les resultats d'une enquete nationale realisee aux Etats-Unis en 1991 et confirment la realite du fait. Ils examinent les facteurs organisationnels, geographiques et individuels qui peuvent expliquer ce phenomene