<p>This dissertation considers the relationship between peer and individual student interaction. The central finding is that self reported friends play a crucial role in individual behaviors, a role that is more significant than other students in their school. Also, using the network of friendships within a school it is possible to construct new peer effect measures and account for endogenous peer group formation. It is however important to distinguish these peer measures from unobserved individual characteristics that may also influence behavior.</p><p>The first chapter examines the effect of potentially misidentifying the reference group on peer effect estimates. The differential impact of school, grade and friend level peer effects on student decisions to smoke and drink are calculated. Friendship nominations come from the Add Health dataset, where students can list up to 10 friends from the school. The bias due to endogenous peer group formation and simulteneity are considered using various instrumenting strategies. Peer effects are found to be large and significant at the friends level for both delinquency variables. It is possible to show that misidentifying the peer group can result in peer effect estimates that are understated by as much as 40\%.</p><p>The second chapter of the dissertation further examines the role of peer interactions, this time considering the effect of popularity on student academic achievement. Recent work has found a strong positive relationship between these variables. In this chapter I ascertain the robustness of these previous findings to controls for unobserved student heterogeneity using and instrumenting technique and a structural model. The results indicate that popularity influences academic achievement positively in the baseline model. However, instrumenting for popularity or including measures of unobserved student characteristics results in a large drop in the effect of popularity, and leads to a significantly negative coefficient in the majority of cases. Interestingly, popularity influences future earnings and attitudes positively, where this effect is robust to the inclusion of unobserved type. Policy simulations where students are redistributed based on race or income indicate that the predicted number of friendships and popularity fall but academic achievement increases. Since student popularity increases happiness and earnings, the overall effect of the redistribution policies have to be considered before implementation.</p> / Dissertation

Multiple facets of perceived value perceptions drive loyalty intentions. However, this value-loyalty link is not uniform for all customers. In fact, the present study identifies three different segments that are internally consistent and stable across different service industries, using two data sets: the wireless telecommunication industry (sample size 1,122) and the financial services industry (sample size 982). Comparing the results of a single-class solution with finite mixture results confirms the existence of unobserved customer segments. The three segments found are characterized as "rationalists", "functionalists" and "value maximizers". These results point the way for value-based segmentation in loyalty initiatives and reflect the importance of a multidimensional conceptualization of perceived value, comprising cognitive and affective components. The present results substantiate the fact that assuming a homogeneous value-loyalty link provides a misleading view of the market. The paper derives implications for marketing research and practice in terms of segmentation, positioning, loyalty programs and strategic alliances. (authors' abstract)

The measurement of human immunodeficiency virus ribonucleic acid levels over time leads to censored longitudinal data. Suitable models for dynamic modelling of these levels need to take this data characteristic into account. If groups of patients with different developments of the levels over time are suspected the model class of finite mixtures of mixed effects models with censored data is required.We describe the model specification and derive the estimation with a suitable expectation-maximization algorithm.We propose a convenient implementation using closed form formulae for the expected mean and variance of the truncated multivariate distribution. Only efficient evaluation of the cumulative multivariate normal distribution function is required. Model selection as well as methods for inference are discussed. The application is demonstrated on the clinical trial ACTG 315 data.

Many potential benefits of new product introductions (NPI) have been identified in existing literature, yet there are empirical and theoretical evidence that suggests that such benefits are not assured. Building on the concepts of time compression diseconomies, absorptive capacity, and time diversification, we argue that benefits that a firm derives from introducing new products depend on the process of NPI, which we conceptualize as how and what products are introduced by the firm. We propose that pace, rhythm, and the scope are three important characteristics of the process of NPI that affect firm value. Further, we argue that this effect is moderated by organizational marketing and technological intensities. We use an unbalanced panel dataset of the products introduced by public firms between 1991 and 2015 to investigate the proposed framework in the bio-pharmaceutical industry. We estimate the proposed model using a multilevel modeling framework, accounting for endogeneity, unobserved heterogeneity, and heteroscedasticity. The proposed framework and modeling approach provide empirical support for the role of pace, rhythm and scope of NPI on firm performance, and guide managers on choosing the right growth strategy to improve new product performance.

In the first chapter of this thesis, we investigate the impact of human capital and wage structure on the gender pay in a panel of European countries using a newly available and appropriate database for cross-country comparisons and a comparable methodology for each country. Our first question is : What role do certain individual characteristics and choices of working men and women play in shaping the cross-country differences in the gender pay gap? What is the exact size of the gender pay gap using the “more appropriate” database available for our purpose? Giving that there are mainly only two harmonized data-sets for comparing gender pay gap throughout Europe: the European Community Household Panel (ECHP) and the European Structure of Earning Survey (ESES). Each database having its shortages: the main weakness of the ECHP is the lack of perfect reliability of the data in general and of wages in particular. However the main advantage of this database is the panel-data dimension and the information on both households and individuals. The data of the ESES is, on the contrary, of a very high standard but it only covers the private sector and has a cross-sectional dimension. Furthermore only few countries are currently available : Denmark, Belgium, Spain, Ireland and Italy. We use the European Structure of Earning Survey (ESES) to analyse international differences in gender pay gaps in the private sector based on a sample of five European economies: Belgium, Denmark, Ireland, Italy and Spain. Using different methods, we examine how wage structures, differences in the distribution of measured characteristics and occupational segregation contribute to and explain the pattern of international differences. Furthermore, we take account of the fact that indirect discrimination may influence female occupational distributions. We find these latter factors to have a significant impact on gender wage differentials. However, the magnitude of their effect varies across countries. In the second chapter, we analyse the persistence of the gender pay differentials over time in Europe and better test the productivity hypothesis by taking into account unobserved heterogeneity. Our second question is : What is the evolution of the pay differential between men and women over a period of time in Europe? And what is the impact of unobserved heterogeneity? The researcher here provides evidence on the effects of unobserved individual heterogeneity on estimated gender pay differentials. Using the European Community Household Panel (ECHP), we present a cross-country comparison of the evolution of unadjusted and adjusted gender pay gaps using both cross-section and panel-data estimation techniques. The analysed countries differ greatly with respect to labour market legislation, bargaining practices structure of earnings and female employment rates. On adjusting for unobserved heterogeneity, we find a narrowed male-female pay differential, as well as significantly different rates of return on individual characteristics. In particularly, the adjusted wage differential decreases by 7 per cent in Belgium, 14 per cent in Ireland, between 20-30 per cent Germany, Italy, the Netherlands and Spain and of 41 per cent and 54 per cent in the UK and in Denmark respectively. In the third chapter, we investigate causes of the gender pay gap beyond the gender differences in observed and unobserved productive characteristics or simply the sex. Explanations of the gender pay gap may be the penalty women face for having children. Obviously, the motherhood wage penalty is relevant to larger issues of gender inequality given that most women are mothers and that childrearing remains a women’s affair. Thus, any penalty associated with motherhood but not with fatherhood affects many women and as such contributes to gender inequalities as the gender pay gap. Furthermore, the motherhood wage effect may be different along the wage distribution as women with different earnings may not be equal in recognising opportunities to reconcile their mother’s and earner’s role. This brings us to our third question. Our third question is : What is the wage effect for mothers of young children in the household? And does it vary along the wage distribution of women? This chapter provides more insight into the effect of the presence of young children on women’s wages. We use individual data from the ECHP (1996-2001) and both a generalised linear model (GLM) and quantile regression (QR) techniques to estimate the wage penalty/bonus associated with the presence of children under the age of sixteen for mothers in ten EU Member States. We also correct for potential selection bias using the Heckman (1979) correction term in the GLM (at the mean) and a selectivity correction term in the quantile regressions. To distinguish between mothers according to their age at the time of their first birth, wage estimations are carried out, separately, for mothers who had their first child before the age of 25 (‘young mothers’) and mothers who had their first child after the age of 25 (‘old mothers’). Our results suggest that on average young mothers earn less than non-mothers while old mothers obtain a gross wage bonus in all countries. These wage differentials are mainly due to differences in human capital, occupational segregation and, to a lesser extent, sectoral segregation between mothers and non-mothers. This overall impact of labour market segregation, suggests a “crowding” explanation of the family pay gap – pay differential between mothers and non-mothers. Nevertheless, the fact that we still find significant family pay gaps in some countries after we control for all variables of our model suggests that we cannot reject the “taste-based” explanation of the family gap in these countries. Our analysis of the impact of family policies on the family pay gap across countries has shown that parental leave and childcare policies tend to decrease the pay differential between non-mothers and mothers. Cash and tax benefits, on the contrary, tend to widen this pay differential. Sample selection also affects the level of the mother pay gap at the mean and throughout the wage distribution in most countries. Furthermore, we find that in most countries inter-quantile differences in pay between mothers and non-mothers are mainly due to differences in human-capital. Differences in their occupational and sectoral segregation further shape these wage differentials along the wage distribution in the UK, Germany and Portugal in our sample of young mothers and in Spain in the sample of old mothers. In the fourth chapter, we analyse the combined effect of motherhood and the family status on women’s wage. Our fourth question is : Is there a lone motherhood pay gap in Europe? And does it vary along the wage distribution of mothers? Substantial research has been devoted to the analysis of poverty and income gaps between households of different types. The effects of family status on wages have been studied to a lesser extent. In this chapter, we present a selectivity corrected quantile regression model for the lone motherhood pay gap – the differential in hourly wage between lone mothers and those with partners. We used harmonized data from the European Community Household Panel and present results for a panel of European countries. We found evidence of lone motherhood penalties and bonuses. In our analysis, most countries presented higher wage disparities at the top of the wage distribution rather than at the bottom or at the mean. Our results suggest that cross-country differences in the lone motherhood pay gap are mainly due to differences in observed and unobserved characteristics between partnered mothers and lone mothers, differences in sample selection and presence of young children in the household. We also investigated other explanations for these differences such as the availability and level of childcare arrangements, the provision of gender-balanced leave and the level of child benefits and tax incentives. As expected, we have found significant positive relationship between the pay gap between lone and partnered mothers and the childcare, take-up and cash and tax benefits policies. Therefore improving these family policies would reduce the raw pay gap observed.

Consumer segmentation based on expenditure are usually done by using observedcharacteristics, such as age and income. This thesis highlights the problem with negativeexternalities which Venice suffers from, due to mass tourism. This thesis aims to assesswhether unobservable heterogeneity can be used to detect latent classes within tourismexpenditure. Segmenting the tourism market using this approach is valuable for policy making.Segmenting is also useful for the actors in the market to identify and attract high spenders. Inthat way, a destination may uphold a sustainable level of tourism instead of increasing touristnumbers. The method used for this approach is finite mixture modelling (FMM), which is notmuch used within consumer markets and therefore this thesis also contributes to tourismexpenditure methodology. This thesis adds to the literature by increasing the knowledge aboutthe importance of unobserved factors when segmenting visitors.The results show that four latent classes are found in tourism expenditure. Some of thevariables, which are significant in determining tourism expenditure, are shown to affectexpenditure differently in different classes while some are shown not to be significant. Theconclusions are that segmenting tourism expenditure, using unobserved heterogeneity, issignificant and that variables, which are barely significant in determining the expenditure ofthe population, can be strongly significant in determining the expenditure for a certain class.

This dissertation contains three essays on firm-sponsored training. Paper 1 develops a general theoretical framework in a frictional labour market to investigate how firms decide to sponsor how much general as well as specific training to workers assuming complementarity between the two types of training as well as education. It shows that firms’ profit maximizing decisions provide firms with an incentive to provide more training, general as well specific, to the more educated workers, more training for more educated workers may lead to low turnover rate, and the resulting life-time profile of firm-sponsored training is U-shaped or decreasing. The policy implications are that governments can subsidize both education and training to improve efficiency. Paper 2 and paper 3 try to provide empirical evidence from different perspectives, respectively determinants and effects of three types of firm-sponsored training, i.e., class-room training, on-the-job-training, and career-related but not job directly related training based on Statistics Canada’s Worker Place and Employee Survey (WES) of 2003/2004. The major empirical findings arising from our estimation results are: (1) Education is positively and significantly associated with the incidence of all three types of training, and significantly positively correlated with the intensity of on-the-job training. (2) Workers in larger firms are more likely to obtain classroom training and on-the-job training than workers in smaller firms. (3) Job tenure is significant and negative for the intensity of classroom training or on-the-job training. (4) Classroom-training and on-the-job training increases the average earnings of workers but less than average resultant firm-level productivity growth. Firm sponsored career related training has no significant impact on a worker’s earnings but increases the firm’s productivity significantly. All these findings by and large are consistent with the theory developed in first paper.

This dissertation contains three essays on firm-sponsored training. Paper 1 develops a general theoretical framework in a frictional labour market to investigate how firms decide to sponsor how much general as well as specific training to workers assuming complementarity between the two types of training as well as education. It shows that firms’ profit maximizing decisions provide firms with an incentive to provide more training, general as well specific, to the more educated workers, more training for more educated workers may lead to low turnover rate, and the resulting life-time profile of firm-sponsored training is U-shaped or decreasing. The policy implications are that governments can subsidize both education and training to improve efficiency. Paper 2 and paper 3 try to provide empirical evidence from different perspectives, respectively determinants and effects of three types of firm-sponsored training, i.e., class-room training, on-the-job-training, and career-related but not job directly related training based on Statistics Canada’s Worker Place and Employee Survey (WES) of 2003/2004. The major empirical findings arising from our estimation results are: (1) Education is positively and significantly associated with the incidence of all three types of training, and significantly positively correlated with the intensity of on-the-job training. (2) Workers in larger firms are more likely to obtain classroom training and on-the-job training than workers in smaller firms. (3) Job tenure is significant and negative for the intensity of classroom training or on-the-job training. (4) Classroom-training and on-the-job training increases the average earnings of workers but less than average resultant firm-level productivity growth. Firm sponsored career related training has no significant impact on a worker’s earnings but increases the firm’s productivity significantly. All these findings by and large are consistent with the theory developed in first paper.

This thesis contains three essays in microeconometrics and applied labor economics. In the first two essays, we estimate dynamic models of schooling choices and employment contract outcomes of the French population. The first essay focuses on the comparison between second-generation immigrants from Africa and their French-natives counterparts. We show that the gap in higher education attainments between those two sub-populations is mainly explained by parents' background and that schooling investment is the main determinant of the gap in permanent employment. The second essay investigates the role played by educational attainments on the employment contract transitions in the early career. We find that a first fixed term contract has a positive impact on the probability of employment in a permanent contract, except for a limited set of the population endowed with particular schooling attainments and unobserved characteristics. Globally, schooling attainments account for around one third of the variance in the probability of permanent employment. The third essay is devoted to the analysis of intra-firm promotions of American executives. We estimate a dynamic model of promotions, in which we disentangle the spurious and the causal impacts of the speed of past advancement. We find that the principal determinant of promotions is unobserved heterogeneity and that the speed of past advancement in the firm's hierarchy (fast tracks) does not have a causal impact on promotions. Functional area has a high explanatory power in promotion outcomes. / Cette thèse présente trois essais en microéconométrie et économie du travail appliquée. Dans les deux premiers essais, nous estimons des modèles dynamiques de choix d'éducation et de contrats de travail en France. Le premier essai s'intéresse à la comparaison entre immigrés de deuxième génération originaires d'Afrique et natifs de parents français. Nous montrons que l'écart dans l'accès aux diplômes d'éducation supérieure entre ces deux sous-populations est expliqué principalement par l'environnement parental et que l'investissement en scolarité est le principal déterminant de l'écart dans l'accès à l'emploi permanent. Le deuxième essai s'intéresse au rôle joué par la scolarité dans les transitions entre contrats de travail en début de carrière. Nous trouvons qu'un premier contrat à durée fixe a un impact positif sur la probabilité d'emploi dans un contrat permanent, excepté pour une partie limitée de la population, dotée de niveaux de scolarité et de caractéristiques inobservables particulières. Globalement, le niveau de scolarité atteint explique environ un tiers de la variance de la probabilité d'emploi permanent. Le troisième essai est dédié à l'analyse des promotions intra-firme de cadres américains. Nous estimons un modèle dynamique de promotion dans lequel nous séparons l'effet causal de l'effet artificiel de la vitesse des avancements passés. Nous trouvons que le principal déterminant des promotions est l'hétérogénéité individuelle inobservable et que la vitesse antérieure de progression dans la hiérarchie de la firme (fast tracks) n'a pas d'impact causal. La division d'appartenance dans l'entreprise a un fort pouvoir explicatif dans les promotions observées.

Travel demand forecasting is essential for many decisions, such as infrastructure investments and policy measures. Traditionally travel demand modelling has considered trip frequency, mode, destination and route choice. This thesis considers two other choice dimensions, hypothesised to have implications for travel demand forecasting. The first part investigates how the increased possibilities to overcome space that ICT (information and communication technology) provides, can be integrated in travel demand forecasting models. We find that possibilities of modelling substitution effects are limited, irrespective of data source and modelling approach. Telecommuting explains, however, a very small part of variation in work trip frequency. It is therefore not urgent to include effects from telecommuting in travel demand forecasting. The results indicate that telecommuting is a privilege for certain groups of employees, and we therefore expect that negative attitudes from management, job suitability and lack of equipment are important obstacles. We find also that company benefits can be obtained from telecommuting. No evidences that telecommuting gives rise to urban sprawl is, however, found. Hence, there is ground for promoting telecommuting from a societal, individual and company perspective. The second part develops a departure time choice model in a mixed logit framework. This model explains how travellers trade-off travel time, travel time variability, monetary and scheduling costs, when choosing departure time. We explicitly account for correlation in unobserved heterogeneity over repeated SP choices, which was fundamental for accurate estimation of the substitution pattern. Temporal constraints at destination are found to mainly restrict late arrival. Constraints at origin mainly restrict early departure. Sensitivity to travel time uncertainty depends on trip type and intended arrival time. Given appropriate input data and a calibrated dynamic assignment model, the model can be applied to forecast peak-spreading effects in congested networks. Combined stated preference (SP) and revealed preference (RP) data is used, which has provided an opportunity to compare observed and stated behaviour. Such analysis has previously not been carried out and indicates that there are systematic differences in RP and SP data. / QC 20100825