Wpływ zanieczyszczenia powietrza na płodność

Together with fast economic growths in recent decades and subsequent environmental pollutions, fertility rates have declined dramatically in China. Considering fertility intention is an essential predictor for fertility rate, we examine the effect of air pollution on fertility intentions in China. Using data from the China General Social Survey (CGSS) collected in 2010 and 2013, we find a negative and significant impact of air pollution on people’s fertility intentions. More importantly, after we restrict the sample to people who have been living in current places for a long period of time, the estimated effect of air pollution decreases but remains significant, indicating existence of endogeneity of air pollution on fertility intentions. For the government to take measures to raise fertility rates in China, it is important to take into account the factor of air pollution.Wraz z szybkim wzrostem gospodarczym w ostatnich dziesięcioleciach i późniejszym zanieczyszczeniem środowiska, wskaźniki dzietności w Chinach dramatycznie spadły. Biorąc pod uwagę, że intencja płodności jest podstawowym predyktorem współczynnika dzietności, badamy wpływ zanieczyszczenia powietrza na intencje dzietności w Chinach. Korzystając z danych z China General Social Survey (CGSS), zebranych w 2010 i 2013 r., wskazujemy na negatywny i znaczący wpływ zanieczyszczenia powietrza na intencje ludzi w zakresie płodności. Co ważniejsze, po ograniczeniu próby do osób, które mieszkają w obecnych miejscach od dłuższego czasu, szacowany wpływ zanieczyszczenia powietrza maleje, ale pozostaje znaczący, wskazując na istnienie endogeniczności zanieczyszczenia powietrza na intencje płodności. Stwierdzamy, że aby rząd mógł podjąć działania mające na celu podniesienie współczynnika dzietności w Chinach, konieczne jest uwzględnienie czynnika zanieczyszczenia powietrza

Reassessing the differential impact of grandmothers and grandfathers : The Old AgeProgram in Nepal

We study the effects on infant mortality of the introduction in 1995 of a non-contributoryuniversal pension scheme in Nepal known as the Old age Allowance Program. We use cross-sectional data from the 1996 and 2001 Nepal Demographic and Health Surveys. Following astandard diff-in-diffs approach, we find positive and significant effects on survival rates for thepresence in the same household of a female beneficiary while negative and sometimes significanteffects for the presence of a male beneficiary. When we conduct pre-treatment common trendtests, we find that we cannot reject it for the case of the female beneficiaries but we stronglyreject it for the case of male beneficiaries. Following Mora and Reggio (2012), we then propose amore flexible model and identification strategy and find that there are no differences in the femaleand the male beneficiary effects. We interpret these results as suggestive that cross-sectionalanalysis may bias downwards the estimates of the effect of grandfathers because of genderdifferences in endogenous household formation.We acknowledge financial help from the Spanish government through grant ECO2012-3135

The comparison of normalization procedures based on different classification systems

In this paper, we develop a new methodology for comparing normalization procedures based on different classification systems. Firstly, a pair of normalization procedures should be compared using their own classification systems for evaluation purposes. Secondly, when the two procedures are noncomparable according to the above test, then evaluation using a third (or more) classification systems may be forthcoming. In the empirical part of the paper we use: (i) the IDCP method for the evaluation of normalization procedures; (ii) two nested classification systems consisting of 219 sub-fields and 19 fields, together with a systematic and a random assignment of articles to sub-fields (or fields) with the aim of maximizing or minimizing differences across sub-fields (or fields); (iii) six normalization procedures using mean citations in each of the classification systems as normalization factors, and (iv) a large dataset, indexed by Thomson Reuters, in which 4.4 million articles published in 1998-2003 with a five-year citation window are assigned to Web of Science subject-categories, or sub-fields using a fractional approach. The results obtained indicate that this methodology may lead to useful conclusions in specific instances.The authors acknowledge financial support by Santander Universities Global Division of Banco Santander. Ruiz-Castillo also acknowledges financial help from the Spanish MEC through grant ECO2010-1959

The impact of extreme observations in citation distributions

This paper studies the role of extremely highly cited articles in two instances: the measurement of citation inequality, and mean citation rates. Using a dataset, acquired from Thomson Scientific, consisting of 4.4 million articles published in 1998-2003 in 22 broad fields with a five-year citation window, the main results are the following. Firstly, both within each of 22 broad fields and in the all-sciences case, citation inequality is strongly affected by the presence of a handful of extreme observations, particularly when it is measured by citation inequality indices that are very sensitive to citation differences in the upper tail of citation distributions. Secondly, the impact of extreme observations on citation averages is generally much smaller. The concluding Section includes some practical lessons for students of citation inequality and/or users of high-impact indicatorsThe authors acknowledge financial support by Santander Universities Global Division of Banco Santander. Ruiz- Castillo also acknowledges financial help from the Spanish MEC through grant ECO2011-2976

Three essays on applied economics

This thesis focuses on the application of empirical research methods to different economic topics. The first chapter examines production effects of subsidies with different characteristics. The second chapter evaluates the impact of an oldage pension program on the welfare of the recipient’s family members. The third chapter applies an income inequality model to study the influence of differences in citation practices across scientific fields on the overall citation inequality. Chapter 1, “Differential Effects on Output Levels of Binding and non-Binding Subsidies under Capitalization”. Subsidies on outputs or inputs are usually production-promoting by lowering the marginal cost. However, if subsidies are binding, i.e. outputs or inputs are partially subsidized, subsidies don’t affect the output level. If subsidies capitalize into input prices, i.e. subsidies benefit both the recipients and input providers, outputs will be negatively affected. My paper contributes by empirically assessing production effects of subsidies taking into account both bindingness and capitalization. I study cattle payments under the Common Agricultural Policy (CAP) implemented in the European Union (EU). I set up a simple model to analyze production effects of these payments. I also estimate the effects with Spanish farm-level data. CAP 1992 and Agenda 2000 are two policy programs of the CAP. Both are designed to reduce over-production in agriculture. Estimation results suggest that cattle payments have negative impacts on outputs when they are binding under CAP 1992, and positive impacts when they are non-binding under Agenda 2000. Chapter 2, “Reassessing the Differential Impact of Grandmothers and Grandfathers: The Old Age Program in Nepal” (co-authored with Ricardo Mora). We study the effects on infant mortality of the introduction in 1995 of a non-contributory universal pension scheme in Nepal known as the Old age Allowance Program. We use cross-sectional data from the 1996 and 2001 Nepal Demographic and Health Surveys. Following a standard diff-in-diffs approach, we find positive and significant effects on survival rates for the presence in the same household of a female beneficiary while negative and sometimes significant effects for the presence of a male beneficiary. When we conduct pre-treatment common trend tests, we find that we cannot reject it for the case of the female beneficiaries but we strongly reject it for the case of male beneficiaries. Following Mora and Reggio (2012), we then propose a more flexible model and identification strategy and find that there are no differences in the female and the male beneficiary effects. We interpret these results as suggestive that cross-sectional analysis may bias downwards the estimates of the effect of grandfathers because of gender differences in endogenous household formation. Chapter 3 is a combination of two closely related papers, namely “The Measurement of the Effect on Citation Inequality of Differences in Citation Practices across Scientific Fields” (co-authored with Juan A. Crespo and Javier Ruiz-Castillo, published in PLoS ONE 8(3): e58727 (2013)), and “The Effect on Citation Inequality of Differences in Citation Practices at the Web of Science Subject Category Level” (co-authored with Juan A. Crespoa, Neus Herranz and Javier Ruiz-Castillo, published in Journal of the American Society for Information Science and Technology, 65:1244-1256, (June 2014)). We introduce a novel method for measuring which part of overall citation inequality can be attributed to differences in citation practices across scientific fields. In addition, we implement an empirical strategy for making meaningful comparisons between the numbers of citations received by articles in different scientific fields. Using a dataset of 4.4 million articles published in 1998-2003 with a five-year citation window, we find that differences in citation practices between the 22 fields account for about 14% of overall citation inequality. When the classification system goes from 22 fields to 219 sub-fields, the effect on citation inequality increases to about 18%. For comparisons of citation counts across fields, we provide a set of exchange rates (ERs) to express citations in any field into citations in the all-fields case. When the raw citation data are normalized with our ERs, the effect of differences in citation practices is reduced to around 2% of overall citation inequality in the case of 22 fields. In the case of 219 sub-fields with the fractional strategy, the normalization of the raw data using the ERs (or sub-field mean citations) as normalization factors reduces the effect to 3.8% (3.4%) of overall citation inequality. The results with the fractional strategy are essentially replicated when we adopt a multiplicative approach.Programa Oficial de Doctorado en EconomíaPresidente: Joan Crespo Fernández; Secretario: Jesús María Carro Prieto; Vocal: Fernando Martín Aragón Sánche

Differences in citation impact across scientific fields

This paper has two aims: (i) to introduce a novel method for measuring which part of overall citation inequality can be attributed to differences in citation practices across scientific fields, and (ii) to implement an empirical strategy for making meaningful comparisons between the number of citations received by articles in the 22 broad fields distinguished by Thomson Scientific. The paper is based on a model in which the number of citations received by any article is a function of the article’s scientific influence, and the field to which it belongs. The model includes a key assumption according to which articles in the same quantile of any field citation distribution have the same degree of citation impact in their respective field. Using a dataset of 4.4 million articles published in 1998-2003 with a five-year citation window, we find that differences in citation practices between the 22 fields account for about 14% of overall citation inequality. Our empirical strategy for making comparisons of citation counts across fields is based on the strong similarities found in the behavior of citation distributions over a large quantile interval. We obtain three main results. Firstly, we provide a set of exchange rates to express citations in any field into citations in the all-fields case. (This can be done for articles in the interval between, approximately, the 71st and the 99th percentiles of their citation distributions). The answer is very satisfactory for 20 out of 22 fields. Secondly, when the raw citation data is normalized with our exchange rates, the effect of differences in citation practices is reduced to, approximately, 2% of overall citation inequality in the normalized citation distributions. Thirdly, we provide an empirical explanation of why the usual normalization procedure based on the fields’ mean citation rates is found to be equally successful.The authors acknowledge financial support by Santander Universities Global Division of Banco Santander. Crespo and Ruiz-Castillo also acknowledge financial help from the Spanish MEC through grants SEJ2007-67436 and ECO2010-1959

The measurement of the effect on citation inequality of differences in citation practices across scientific fields

This paper has two aims: (i) to introduce a novel method for measuring which part of overall citation inequality can be attributed to differences in citation practices across scientific fields, and (ii) to implement an empirical strategy for making meaningful comparisons between the number of citations received by articles in 22 broad fields. The number of citations received by any article is seen as a function of the article's scientific influence, and the field to which it belongs. A key assumption is that articles in the same quantile of any field citation distribution have the same degree of citation impact in their respective field. Using a dataset of 4.4 million articles published in 1998-2003 with a five-year citation window, we estimate that differences in citation practices between the 22 fields account for 14% of overall citation inequality. Our empirical strategy is based on the strong similarities found in the behavior of citation distributions. We obtain three main results. Firstly, we estimate a set of average-based indicators, called exchange rates, to express the citations received by any article in a large interval in terms of the citations received in a reference situation. Secondly, using our exchange rates as normalization factors of the raw citation data reduces the effect of differences in citation practices to, approximately, 2% of overall citation inequality in the normalized citation distributions. Thirdly, we provide an empirical explanation of why the usual normalization procedure based on the fields' mean citation rates is found to be equally successful.The authors acknowledge financial support by Santander Universities Global Division of Banco Santander. Crespo and Ruiz-Castillo also acknowledge financial help from the Spanish MEC through grants SEJ2007-67436 and ECO2010-1959

Quantitative evaluation of alternative field normalization procedures

ide differences in publication and citation practices makes impossible the direct comparison of raw citation counts across scientific disciplines. Recent research has studied new and traditional normalization procedures aimed at suppressing as much as possible these disproportions in citation numbers among scientific domains. Using the recently introduced IDCP (Inequality due to Differences in Citation Practices) method, this paper rigorously tests the performance of six cited-side normalization procedures based on the Thomson Reuters classification system consisting of 172 subfields. We use six yearly datasets from 1980 to 2004, with widely varying citation windows from the publication year to May 2011. The main findings are the following three. Firstly, as observed in previous research, within each year the shapes of sub-field citation distributions are strikingly similar. This paves the way for several normalization procedures to perform reasonably well in reducing the effect on citation inequality of differences in citation practices. Secondly, independently of the year of publication and the length of the citation window, the effect of such differences represents about 13% of total citation inequality. Thirdly, a recently introduced two-parameter normalization scheme outperforms the other normalization procedures over the entire period, reducing citation disproportions to a level very close to the minimum achievable given the data and the classification system. However, the traditional procedure of using sub-field mean citations as normalization factors yields also good results.Ruiz-Castillo acknowledges financial help from the Spanish MEC through grant ECO2011-2976

The effect on citation inequality of differences in citation practices at the Web of Sciences subject category level

This paper studies the impact of differences in citation practices at the sub-field, or Web of Science subject category level using the model introduced in Crespo et al. (2012) according to which the number of citations received by an article depends on its underlying scientific influence and the field to which it belongs. We use the same Thomson Reuters dataset of about 4.4 million articles published in 1998-2003 with a fiveyear citation window used in Crespo et al. (2013) to analyze a classification system consisting of 22 broad fields. The main results are the following four. Firstly, as expected, when the classification system goes from 22 broad fields to 219 sub-fields the effect on citation inequality of differences in citation practices increases from approximately 14% at the field level to 18% at the sub-field level. Secondly, we estimate a set of exchange rates (ERs) to express the citation counts of articles in a wide quantile interval into the equivalent counts in the all-sciences case. For example, in the fractional case we find that in 187 out of 219 sub-fields the ERs are reliable in the sense that the coefficient of variation is smaller than or equal to 0.10. ERs are estimated over the [660, 978] interval that, on average, covers about 62% of all citations. Thirdly, in the fractional case the normalization of the raw data using the ERs (or sub-field mean citations) as normalization factors reduces the importance of the differences in citation practices from 18% to 3.8% (3.4%) of overall citation inequality. Fourthly, the results in the fractional case are essentially replicated when we adopt the multiplicative approac