Negli anni ’80, paesi in via di sviluppo (DCs) e paesi meno sviluppati (PMS) hanno subito cambiamenti strutturali, muovendosi da politiche di sostituzione di importazione a strategie di liberalizzazione. Questi paesi hanno assistito ad una crescita dinamica risultata dall’aumento della produttività dovuto alla maggiore esposizione delle industrie locali alla concorrenza, dall'aumento delle importazioni tecnologiche incarnate in capitale e in beni intermedi, e ad una maggiore diffusione di conoscenze e informazioni. Questo lavoro esamina come liberalizzazione commerciale ed aggiornamento tecnologico abbiano influito sull’occupazione in paesi DCs e PMS, e studia il fenomeno del cambiamento tecnologico skill biased. Si esaminano il settore manifatturiero turco tra il 1980-2001 e quello etiope tra il 1996-2004. Questo studio, basato sul System Generalized Method of Moments (GMM-SYS), implementa un quadro dinamico di due equazioni che raffigurano tendenze occupazionali a livello enterprise per lavoratori qualificati e non qualificati. I risultati confermano l'aspettativa teorica che DCs e LDC affrontano fenomeni di skill-biased technological change e incrementano il potere d’importazione di tecnologia, aumentando il divario d’occupazione tra lavoratori qualificati e non qualificati. Tuttavia, le cause specifiche di skill-bias e la portata del loro effetto possono variare in base a diverse infrastrutture istituzionali e capacità nazionali. / In the 1980's developing countries (DCs) and least developed countries (LDCs) underwent structural changes, moving from import substitution policies to liberalization strategies. These countries witnessed a dynamic growth effect that emerges from productivity growth due to increased exposure of local industries to competition, increased technological imports embodied in capital and intermediate goods, and to the transfer of knowledge. This work looks into the employment impact of trade liberalization and technological upgrading in DCs and LDCs, and studies the phenomenon of skill biased technological change in those countries. It takes the case of the Turkish manufacturing sector for the period 1980 - 2001, and the case of the Ethiopian manufacturing sector for the period 1996 - 2004. It deploys System Generalized Method of Moments (GMM-SYS) procedure to this effect, implementing a two-equation dynamic framework that depicts enterprise-level employment trends separately for skilled and unskilled workers. The results confirm the theoretical expectation that DCs and LDCs face the phenomena of skill-biased technological change and skill-enhancing technology import, both leading to increasing the employment gap between skilled and unskilled workers. However, the specific determinants of skill bias and the size of their effect can differ due to diverse institutional infrastructures and national capabilities.

This doctoral thesis consists of three essays within the field of economics of information privacy examined through the lens of behavioral and experimental economics. Rapid development and expansion of Internet, mobile and network technologies in the last decades has provided multitudinous opportunities and benefits to both business and society proposing the customized services and personalized offers at a relatively low price and high speed. However, such innovations and progress have also created complex and hazardous issues. One of the main problems is related to the management of extensive flows of information, containing terabytes of personal data. Collection, storage, analysis, and sharing of this information imply risks and trigger usersâ concerns that range from nearly harmless to significantly pernicious, including tracking of online behavior and location, intrusive or unsolicited marketing, price discrimination, surveillance, hacking attacks, fraud, and identity theft. Some users ignore these issues or at least do not take an action to protect their online privacy. Others try to limit their activity in Internet, which in turn may inhibit the online shopping acceptance. Yet another group of users gathers personal information protection, for example, by deploying the privacy-enhancing technologies, e.g., ad-blockers, e-mail encryption, etc. The ad-blockers sometimes reduce the revenue of online publishers, which provide the content to their users for free and do not receive the income from advertisers in case the user has blocked ads. The economics of privacy studies the trade-offs related to the positive and negative economic consequences of personal information use by data subjects and its protection by data holders and aims at balancing the interests of both parties optimising the expected utilities of various stakeholders. As technology is penetrating every aspect of human life raising numerous privacy issues and affecting a large number of interested parties, including business, policy-makers, and legislative regulators, the outcome of this research is expected to have a great impact on individual economic markets, consumers, and society as a whole. The first essay provides an extensive literature review and combines the theoretical and empirical evidence on the impact of advertising in both traditional and digital media in order to gain the insights about the effects of ad-blocking privacy-enhancing technologies on consumersâ welfare. It first studies the views of the main schools of advertising, informative and persuasive. The informative school of advertising emphasizes the positive effects of advertising on sales, competition, product quality, and consumersâ utility and satisfaction by matching buyers to sellers, informing the potential customers about available goods and enhancing their informed purchasing decisions. In contrast, the advocates of persuasive school view advertising as a generator of irrational brand loyalty that distorts consumersâ preferences, inflates product prices, and creates entry barriers. I pay special attention to the targeted advertising, which is typically assumed to have a positive impact on consumersâ welfare if it does not cause the decrease of product quality and does not involve the extraction of consumersâ surplus through the exploitation of reservation price for discriminating activities. Moreover, the utility of personalized advertising appears to be a function of its accuracy: the more relevant is a targeted offer, the more valuable it is for the customer. I then review the effects of online advertising on the main stakeholders and users and show that the low cost of online advertising leads to excessive advertising volumes causing information overload, psychological discomfort and reactance, privacy concerns, decreased exploration activities and opinion diversity, and market inefficiency. Finally, as ad-blocking technologies filter advertising content and limit advertising exposure, I analyze the consequences of ad-blocking deployment through the lens of the models on advertising restrictions. The control of advertising volume and its partial restriction would benefit both consumers and businesses more than a complete ban of advertising. For example, advertising exposure caps, which limit the number of times that the same ad is to be shown to a particular user, general reduction of the advertising slots, control of the advertising quality standards, and limitation of tracking would result in a better market equilibrium than can offer an arms race of ad-blockers and anti-ad-blockers. Finally, I review the solutions alternative to the blocking of advertising content, which include self regulation, non-intrusive ads programs, paywall, intention economy approach that promotes business models, in which user initiates the trade and not the marketer, and active social movements aimed at increasing social awareness and consumer education. The second essay describes a model of factors affecting Internet usersâ perceptions of websitesâ trustworthiness with respect to their privacy and the intentions to purchase from such websites. Using focus group method I calibrate a list of websitesâ attributes that represent those factors. Then I run an online survey with 117 adult participants to validate the research model. I find that privacy (including awareness, information collection and control practices), security, and reputation (including background and feedback) have strong effect on trust and willingness to buy, while website quality plays a marginal role. Although generally trustworthiness perceptions and purchase intentions are positively correlated, in some cases participants are likely to purchase from the websites that they have judged as untrustworthy. I discuss how behavioral biases and decision-making heuristics may explain this discrepancy between perceptions and behavioral intentions. Finally, I analyze and suggest what factors, particular websitesâ attributes, and individual characteristics have the strongest effect on hindering or advancing customersâ trust and willingness to buy. In the third essay I investigate the decision of experimental subjects to incur the risk of revealing personal information to other participants. I do so by using a novel method to generate personal information that reliably induces privacy concerns in the laboratory. I show that individual decisions to incur privacy risk are correlated with decisions to incur monetary risk. I find that partially depriving subjects of control over the revelation of their personal information does not lead them to lose interest in protecting it. I also find that making subjects think of privacy decisions after financial decisions reduces their aversion to privacy risk. Finally, surveyed attitude to privacy and explicit willingness to pay or to accept payments for personal information correlate with willingness to incur privacy risk. Having shown that privacy loss can be assimilated to a monetary loss, I compare decisions to incur risk in privacy lotteries with risk attitude in monetary lotteries to derive estimates of the implicit monetary value of privacy. The average implicit monetary value of privacy is about equal to the average willingness to pay to protect private information, but the two measures do not correlate at the individual level. I conclude by underlining the need to know individual attitudes to risk to properly evaluate individual attitudes to privacy as such.

This thesis investigates the transformations associated with the development and diffusion of 4.0 technologies, by combining a firm-level perspective with a territorial-level perspective. The aim is to understand whether and to what extent the engagement of firms, in particular technological knowledge-intensive business services, in 4.0 innovation activities is affected by the characteris-tics of the territory, regions, cities, or local production systems, in which they are located. The thesis consists of three chapters. Chapter 1 comprises a systematic literature review of the studies that address Industry 4.0-related issues in industrialized countries from a regional perspective. The selected articles have been systematically collected and then discussed using a qualitative content-based approach. This review allowed for the identification of the main issues discussed and the gaps that exist in the literature and laid the foundation for the empirical analysis conducted in Chapter 2 and Chapter 3, which focus on private technological knowledge-intensive business services (t-KIBS) engaged in the production and/or provision of ICT services. The decision to concentrate on technological knowledge-intensive business services (KIBS) specializing in information and communication technology (ICT) is connected to their significant role in 4.0 transformations as they serve as both producers of these technologies and intermediaries and adapters, facilitating their adoption and implementation. Chapter 2 delves into the examination of the firm level and territorial level factors that influence the spatial distribution of the t-KIBS involved in the provision of 4.0 technologies (4.0 t-KIBS). 4.0 t-KIBS were identified using information extracted from t-KIBS websites, collected through web-scraping techniques. Then, a probit model with sample selection was employed to identify the most important territorial and firm-related factors influencing the decision to develop and/or provide 4.0 technologies. The results show that the probability of mentioning 4.0 technology is positively affected by t-KIBS size and profitability. From a territorial perspective, the main determinants are represented by demand coming from co-located manufacturers and to a lesser extent by urbanization economies. Finally, following the literature on KIBS variety, Chapter 3 explores the heterogeneous nature of the t-KIBS involved in the production and provision of 4.0 technologies. The objective is to gain insights into how these organizations differ across several key dimensions frequently examined in the KIBS variety literature. These dimensions encompass the geographical scope, innovation output, cognitive structure, external collaborations, and client focus. The empirical analysis draws on the same database built for Chapter 2 and on data collected through an original survey of a sample of 500 t-KIBS. The survey allowed for the collection of firm-level information that could not be retrieved from other data sources. The empirical analysis is split into two parts. Using a probit approach, the first part of the analysis explores whether and to what extent the peculiarities of 4.0 t-KIBS vary mainly according to their geographical scope and innovation output. The second part of the analysis employs a matching technique to compare certain attributes of 4.0 t-KIBS with those whose activities are not centred around 4.0 technologies. The main results show that the activities of 4.0 t-KIBS have a broader geographical scope that goes beyond local and regional boundaries. In contrast to established literature on KIBS, this is especially true for those t-KIBS that deliver customized innovations tailored to the needs of customers. From a cognitive perspective, it emerges the tendency of 4.0 t-KIBS to also rely on non-technical knowledge, while in terms of collaborations, they are more likely to collaborate with firms belonging to the same business group. Finally, 4.0 t-KIBS that are regionally anchored (i.e., they have not established an inter-regional network) are more likely to develop services and technologies specifically for public administrations.

Although the last thirty years Regional Innovation Systems (RIS) received great attention by policy makers, only during the last decade social networks were applied in the fields of innovation and regional economics. The majority of the existing empirical studies on networks adopt a static point of view, representing a regional knowledge network at a certain point in time, while there are few recent attempts exploring the evolution of knowledge networks and the dynamics that drive it. The present work aims at covering some of the gaps in the literature, using the dataset on collaborative projects from the ICT activity in Trentino. It introduces an original multidimensional framework to analyze the knowledge flows inside, from within and towards the regional network. It also identifies the key actors inside the region and describes their role in knowledge creation and diffusion. Concerning the spatial and temporal evolution of the knowledge networks, this thesis investigates the preferences of the economic actors operating inside regional networks, in terms of shared characteristics, while it explores the dynamics developed through time by the behavior of economic agents during high and low certainty periods, contributing to the inertia and the resilience of the regional knowledge network. The present research is the first that introduces Social Network Analysis (SNA) using data on knowledge transfer from Trentino, considering the entire universe of actors involved in the regional ICT knowledge network for the last fifteen years, and allocating it to an original multidimensional framework, in order to reveal the value of the knowledge network per se, and the impact of the regional policies on the network and not on the output of the innovation process. On the spatial evolution of networks, it explores in depth the preferences of the actors of a regional knowledge network, in order to make it more solid through strong collaborations. It proves that the effect of every kind of proximity or distance is different, while it introduces the measure of relational proximity, exploring the effect of the position of an actor inside the knowledge network in relation with the rest of the actors. However, the major finding of this thesis is the introduction of the temporal aspect in the evolution of the regional knowledge network, and the exploration of the agent behavior during periods of uncertainty. The introduction in the network evolution of an external negative event, like economic crisis, allows the deduction of useful conclusions on how the actors behave in terms of trust and collaboration creation.

This thesis examines three main themes, firms productive efficiency, internationalisation of African firms, and effect of liberalisation policies on market power and market imperfections. The thesis combines two main strands in economics literature in accessing the three main themes of the papers. The first strand regards methodological approaches to estimate a production function from which productive efficiency can be computed. Consistent estimation of productive efficiency is a necessary condition to analyse firm behaviour and their response to trade policies. The thesis critically examines methodologies to estimate productive efficiency. The second strand, international trade and industrial development, analyse firms behaviour in foreign market as well as firms responses to trade liberalisation policies and their overall impact on structural transformation. The two strands of literature examined in this thesis resulted in three independent papers, each of which addresses specific issues along the spectrum of productive efficiency estimation, internationalisation, and market power.

This PhD dissertation is a collection of four essays focusing on the demand and supply of small business finance in Kenya. The studies are the result of primary research conducted over three years with both demand-side players, more specifically micro and small-scale entrepreneurs operating in a low-income area in Nairobi. And the main suppliers of small businesses finance in Kenya - commercial banks - which provided data on the size, characteristics and evolution of their SME finance portfolio between 2009 and 2013. Since commercial banks are not the only players in the provision of finance to small firms, the dissertation studies the entire financial landscape of both formal and informal financial providers, including institutions such as microfinance institutions, savings groups and moneylenders among others. The dissertation is divided in two parts: the first half of the dissertation analyses the determinants, effects and challenges of access to formal and informal finance by small enterprises in Nairobi (Essays 1 and 2). These two essays use primary data collected through a survey questionnaire with 344 micro and small enterprises in a low income neighbourhood in Nairobi. The analysis describes the financial landscapes in which businesses operate and the effects of access to credit on firm performance (e.g. investments, profitability and employment growth.). The second half of the dissertation analyses the supply-side, more specifically the relation between formal financial sector development and economic growth (Essay 3) and the characteristics and development of bank financing to SMEs (small and medium enterprises) in Kenya (Essay 4). Essay 3 relies on secondary time-series data taken from the World Bank databases, whereas Essay 4 uses original survey data administered to commercial banks in Kenya in two survey rounds in 2012 and 2014. Each essay in this dissertation is a standalone study with its own literature survey, research questions, data and methodological approach. The main findings of the demand-side chapters is that informality has significant effects on access (or exclusion) to bank finance, but is less relevant when we investigate informal financial instruments such as self-help groups and family/friend loans. Essay 2 of the dissertation shows that different types of loans have different effects on the performance of businesses, and that loans from commercial banks seem to incentivize investments and employment creation more than other types of loans. The supply-side chapters on the other hand show that there is a long-term association between financial sector development in Kenya and economic growth, and that there is a reciprocal relation of causality over the long-run. Finally, Essay 4 shows that bank financing to SMEs has grown steadily over the last few years and that banks are increasingly exposed to small businesses in their lending portfolio. However, the financial products to SMEs tend to be unsophisticated and concentrated in few sectors.

This thesis contains four closely related essays which address the empirical issues pertaining to the causes, consequences, and households’ responses to food price shocks in Uganda. The first essay investigates the nature of volatilities in agricultural commodity prices in Uganda between 2000 and 2012 by focusing on six key food staples, namely matooke, cassava, maize, sweet potatoes, beans, and millet flour. It studies the behavior of monthly price volatilities of these commodities, examines the extent of their volatility spillovers, identifies their macroeconomic and environmental drivers, and uncover their differential impacts using respectively the General Autoregressive Conditional Heteroscedastic (GARCH), the Vector Autoregressive (VAR) and the Seemingly Unrelated Regression (SUR) models. I find evidence that both unconditional and conditional price volatilities have significantly increased since January 2008 for most commodities, period of turmoil in the global food markets. The GARCH (1, 1) estimates indicate a strong persistence in volatility for most commodities while results from the Exponential GARCH (1, 1) models suggest the presence of asymmetric and leverage effects of unexpected price shocks for half of the commodities. In addition, the VAR estimation results detect limited and mostly unidirectional spillover effects across food commodities. Finally, historical price volatilities of most commodities are found to be primarily affected by volatilities in consumer price indices, fuel prices, and rainfall, with less evidence of strong seasonality effects as previously reported. The second essay presents an empirical analysis of the welfare impacts of food price changes in Uganda using three waves of the Uganda National Panel Surveys (UNPS) spanning over the years 2005-2011. It theoretically investigates the implications of labor market imperfections and households’ heterogeneity in terms of their net positions in both food and labor markets and compares welfare estimates between separable and non-separable models. Through the estimations a panel stochastic production frontier function and a censored-Quadratic Almost Ideal Demand Systems (QUAIDS) with expenditure and shadow wage endogeneities, the results suggest that the welfare effects of price changes (measured in terms of compensating variations) were globally lower in the non-separable agricultural model, implying a high degree of labor market frictions. Furthermore, I find that the welfare effects were unevenly distributed both within and between household groups. Particularly, although agricultural households benefited from price increases as a group between 2005/6 and 2009/10, both significant and insignificant net buyers did suffer from price changes. Moreover, results from non-parametric estimations show that households at the extremes of the welfare distribution were more severely hit by food price instabilities than others. Finally, the essay suggests that the important dynamics in the net market positions observed during the sample period might be attributed to a cost-benefit analysis related to the potential welfare effects of food prices. The third essay explores the question of crop choices and land allocations in environments where farmers face uncertainties about end-of-season output prices and yield levels, weather variability, and formulate expectations about their future levels. Indeed, in the absence of credit and/or insurance markets, farmers are widely expected to adjust their land allocation decisions as a management tool against agricultural and market-related risks. However, little is actually known about the likely differential effects of each of these risk components on farmers’ decisions, particularly when current decisions are allowed to depend on previous choices. Using a nationally representative panel data set for agricultural households in Uganda spanning over the years 2005 – 2012, the paper proposes to investigate the role played by both price and yield risks on farmers’ crop choices and area allocations using a multivariate generalization of the Heckman-type two-step procedure: a multivariate crop selection and a conditional acreage share models. The crop selection problem is modeled as a dynamic multivariate probit regression and estimated through Simulated Maximum Likelihood and the Geweke Hajivassiliou Keane simulator, whereas the conditional acreage share model is estimated using a dynamic multivariate fractional logit model. In both the multivariate crop selection and acreage share models, the results reveal that, while own expected prices and yields are among the main drivers of farmers' crop choices and land share allocations, farmers are found to be more sensitive to changes in expected yield levels than in expected end-of-season output prices. In addition, yield risks, temperature and rainfall volatility appear to have more impact on acreage share decisions than market price risks. Finally, household characteristics are found to play a marginal role in explaining farmers’ crop selection and acreage allocation decisions. The fourth and last essay develops a modified standard Ramsey model to analyze households’ welfare growth and test the assumption that differential exposure to food price shocks leads to different welfare trajectories and to potentially increased risks of poverty traps. The essay focuses on two welfare indicators, namely consumption levels and asset indices, and employs a battery of econometric methods, ranging from parametric GMM fixed effects models to locally weighted scatterplot smoother (LOWESS), local polynomial regressions, and Ruppert et al’s (2003) semi-parametric penalized splines to address nonlinearities in welfare dynamics, identify and locate critical welfare thresholds, and test for the presence of single against multiple welfare equilibria. Using the full sample, I find nonlinearities in welfare dynamic paths and reduction in the growth rates of both consumption levels and assets holdings as a consequence of exposure to food price and asset shocks. However, there is no evidence of poverty traps caused by households’ exposure or vulnerability to food price shocks, but instead I identify only a single dynamic stable equilibrium, located slightly above the official poverty, towards which Ugandan households are converging in the long run. Finally, when disaggregating households into different sub-groups sharing similar characteristics, the empirical results reveal that Ugandan households are converging towards specific welfare equilibria, depending on their initial conditions, demographic characteristics, the extent of their vulnerability and differential exposure to food price shocks. Particularly, I found that, households exposed to food price shocks or above the vulnerability threshold index are expected to move in the long run to welfare equilibria located at lower levels than their unexposed or less vulnerable counterparts.

The analysis of the complex and fast changing technological processes which today are summarized in the term ‘Industry 4.0’ reveals that the industrial system is shifting towards a new technological paradigm (Perez, 2009; 2010), implying systemic transformations at micro, meso and macro levels of analysis (Geels, 2005). These radical transformations are deeply changing the way products, production processes and business models are conceived, questioning the traditional separation between manufacturing and services, and making it more and more important for firms to adopt a collaborative approach to innovation (Hagedoorn et al., 2000). This rapid technological advance implies the need for the socio-economic players to adopt new strategic and operational measures in order to prevent the loss of competitive advantage of national and regional innovation systems. The recent debate on industrial policies shows that a mission-oriented industrial policy approach (Mazzucato, 2014; European Commission, 2018) may provide interesting inspirational principles able to guide these transformations, since it places at the centre of its reasoning the key role of the public actor able to stimulate the strategic coordination between multiple socio-economic players at different levels (Mazzucato and Perez, 2014; Rodrik, 2004). According to this approach, Public-Private research Partnerships, are assumed to be effective vehicles of governance able to improve technological development, stimulating strong links between the relevant socio-economic players and thus increasing the national and regional systems’ overall innovative potential (Mazzucato, 2014; Rodrik, 2004; 2014; Robin and Schubert, 2013; Kristensen and Scherrer, 2016). The aim of the present work is to understand how the strategic coordination between public and private players may be an opportunity for the definition of effective innovation policies in the context of the current socio-technical transition. In order to reach this purpose, a multilevel approach (Geels, 2005) is adopted, taking into account both the national and the regional levels of analysis. A quantitative analysis is provided at national level in order to understand the relationship between a specific approach to innovation and technology policy, the overall innovation performance and the level of diffusion of cooperative innovation activities in a National Innovation System (Lundvall, 1988); moreover, it contributes to the existing literature on Public-Private research Partnerships (Hagedoorn et al., 2000) by testing the effectiveness of some main variables at industry and company level explaining the propensity of companies to get involved in formal cooperative innovation activities. This analysis is made taking into account data stemming from the 8th wave of the Community Innovation Survey, 2010-2012. Moreover, the results of a field research conducted at regional level are presented, aiming at understanding the elements of an institutional/organizational framework which are able to positively influence technological local development. In this case, the analysis takes into account a Regional Innovation System (Cooke et al., 1997): the Autonomous Province of Trento. Data have been gathered through both primary sources, based on 57 semi-structured interviews to local institutions and firms, and secondary sources, based on relevant documents and reports. The major conclusion of the present work is that, given the systemic nature of this socio-technical transition, only a mission-oriented policy approach to innovation policy based on strategic Public-Private research Partnerships may be able to trigger the necessary cross-level synergies between the different socio-economic players involved, managing the important challenges lying behind these transformations.

This thesis includes three main chapters that are the outcome of different research projects. All chapters stand as independent papers, but they are linked by the common focus on firm financial factors and export behavior, and by the use of microeconometric methodologies applied to firm-level data. The first two chapters investigate, respectively, the impact of export activity on firms’ access to credit and the role of corporate financial structure as a determinant of exporters’ ability to compete on foreign markets through quality. The third chapter looks instead at the scope for promoting investment and exports of small and medium enterprises through the introduction of more favorable Corporate Taxation rates.

Improving agricultural productivity, agricultural commercialization and improving the livelihoods of the population are the main challenges in the Sub-Saharan Africa region where the majority of the population are poor and live in rural areas. Several factors including lack of improved farming practices, poor infrastructure, low level of market integration to the world market and within countries, climate change, and inadequate policy support restrained the performance of the agricultural sector in the region. This thesis consists of four chapters, three empirical and one theoretical chapter. Each of the empirical chapters deals with selected topics pertinent to the agriculture sector in Ethiopia. The theoretical chapter reviews the agricultural policies adopted by the existing government and implemented over the past two decades. After the introductory chapter, the second chapter analyzes the impacts of climate change on crop yields and yield vari-ability in Ethiopia. The impacts of climate change appear to be different across crops and regions. However, the future crop yield levels largely depend on future technological development in farming practices. The third chapter aims to understand the extent of price transmissions from the world markets to domestic grain markets, and the extent of market integration in domestic grain markets. The fourth chapter investigates and compares the volatilities of oilseeds prices in the world and domestic markets. The data used in the second, third and fourth chapters are obtained from various secondary sources. The fifth chapter reviews major agricultural policies implemented over the last two decades and identifies policies that either enhanced the growth of the agricultural sector or holding back its performance. The sixth chapter underlines the main conclusions and indicates future research areas.