Microcredit programs are of great interest to economists and policymakers because of their potential for reducing poverty, particularly among women. The first chapter mainly investigates the effectiveness aspect of microcredit programs. Using program evaluation methods, we find significant improvement in women's economic condition after participating in these programs. This study also corrects for the self-selection bias that might arise due to the fact that women decide on whether to participate in the programs or not. The second chapter studies the determinants of women's economic performance in microcredit programs. These determinants are in the form of different types of characteristics of women: their own characteristics, such as age or schooling or the characteristics of the household or village they live in. One obstacle to measure the effect of observed characteristics is the problem of omitted variable bias, typically caused by unavailability of data on unobserved ability of individuals. In the absence of suitable instruments, this study finds information about unobserved ability from the marriage market. It is found that incorporating estimates of women's unobserved characteristics significantly changes the estimated effect of women's observed characteristics and substantially removes the omitted variable bias. Microcredit programs originated from Bangladesh and now three major microcredit programs are operating: Grameen Bank, BRAC and RD-12. The third chapter investigates how these different microcredit programs have been performing relative to each other. Using similar program evaluation technique as in chapter 1, we measure program impact on women's economic welfare for these programs separately. We find that BRAC outperforms Grameen Bank and RD-12 significantly. This result is interesting since it contradicts the popular notion that Grameen Bank is the most successful microcredit program. This study also tries to find the determinants of economic success of women participating in these programs, separately for each program. These results provide more insights into different aspects of microcredit program. / Ph. D.

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In this thesis the positive relationship between firm size and wages is investigated through the application of hierarchy theories. Many different explanations have been proposed for this relationship, but have met only limited success at best. The strongest finding to date is that unobserved ability is a significant factor. The question of interest here is ???why do wages increase as the size firm increases???? Hierarchy theories take a different approach towards the analysis of firms in comparison to the alternate theories which have dominated previous investigations. As a result of their focus on the organisational relationships within a firm???s internal structure, hierarchy theories offer certain insights to the size-wage relationship which to date have been unnoticed. An empirical investigation into the size-wage differential incorporating structural considerations into an augmented wage equation offers strong support for the propositions of hierarchy theories. I find that half of the firm size effect for workers can be explained by controlling for some aspects of management structure, and that span of control has a discontinuous effect on wages. These results are completely consistent with the existing findings on unobserved ability and have the added attraction of providing economic as well as statistical explanatory power.

<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

In this thesis the positive relationship between firm size and wages is investigated through the application of hierarchy theories. Many different explanations have been proposed for this relationship, but have met only limited success at best. The strongest finding to date is that unobserved ability is a significant factor. The question of interest here is ???why do wages increase as the size firm increases???? Hierarchy theories take a different approach towards the analysis of firms in comparison to the alternate theories which have dominated previous investigations. As a result of their focus on the organisational relationships within a firm???s internal structure, hierarchy theories offer certain insights to the size-wage relationship which to date have been unnoticed. An empirical investigation into the size-wage differential incorporating structural considerations into an augmented wage equation offers strong support for the propositions of hierarchy theories. I find that half of the firm size effect for workers can be explained by controlling for some aspects of management structure, and that span of control has a discontinuous effect on wages. These results are completely consistent with the existing findings on unobserved ability and have the added attraction of providing economic as well as statistical explanatory power.

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.

This thesis consists of four self-contained papers related to energydemand and household cooking energy.Paper [I] examine the impact of price, income and non-economicfactors on gasoline demand using a structural time series model. Theresults indicated that non-economic factors did have an impact ongasoline demand and also one of the largest contributors to changes ingasoline demand in both countries, especially after the 1990s. Theresults from the time varying parameter model (TVP) indicated thatboth price and income elasticities were varying over time, but thevariations were insignificant for both Sweden and the UK. Theestimated gasoline trend also showed a similar pattern for the twocountries, increasing continuously up to 1990 and taking a downturnthereafter.Paper [II] studies whether the commonly used linear parametricmodel for estimating aggregate energy demand is the correctfunctional specification for the data generating process. Parametricand nonparametric econometric approaches to analyzing aggregateenergy demand data for 17 OECD countries are used. The resultsfrom the nonparametric correct model specification test for theparametric model rejects the linear, log-linear and translogspecifications. The nonparametric results indicate that the effect of theincome variable is nonlinear, while that of the price variable is linearbut not constant. The nonparametric estimates for the price variable isrelatively low, approximately −0.2.Paper [III] relaxed the weak separability assumption betweengasoline demand and labor supply by examining the effect of laborsupply, measured by male and female working hours on gasolinedemand. I used a flexible semiparametric model that allowed fordifferences in response to income, age and labor supply, respectively.Using Swedish household survey data, the results indicated that therelationship between gasoline demand and income, age and laborsupply were non-linear. The formal separability test rejects the null ofseparability between gasoline demand and labor supply. Furthermore,there was evidence indicating small bias in the estimates when oneignored labor supply in the model.Paper [IV] investigated the key factors influencing the choice ofcooking fuels in Ghana. Results from the study indicated thateducation, income, urban location and access to infrastructure werethe key factors influencing household’s choice of the main cookingfuels (fuelwood, charcoal and liquefied petroleum gas). The study alsofound that, in addition to household demographics and urbanization,the supply (availability) of the fuels influenced household choice forthe various fuels. Increase in household income was likely to increasethe probability of choosing modern fuel (liquefied petroleum gas andelectricity) relative to solid (crop residue and fuelwood) and transitionfuel (kerosene and charcoal).