A study on time-varying quantile and its applications

This Thesis is the result of my Master Degree studies at the Graduate School of Economics, Getúlio Vargas Foundation, from January 2004 to August 2006. am indebted to my Thesis Advisor, Professor Luiz Renato Lima, who introduced me to the Econometrics' world. In this Thesis, we study time-varying quantile process and we develop two applications, which are presented here as Part and Part II. Each of these parts was transformed in paper. Both papers were submitted. Part shows that asymmetric persistence induces ARCH effects, but the LMARCH test has power against it. On the other hand, the test for asymmetric dynamics proposed by Koenker and Xiao (2004) has correct size under the presence of ARCH errors. These results suggest that the LM-ARCH and the Koenker-Xiao tests may be used in applied research as complementary tools. In the Part II, we compare four different Value-at-Risk (VaR) methodologies through Monte Cario experiments. Our results indicate that the method based on quantile regression with ARCH effect dominates other methods that require distributional assumption. In particular, we show that the non-robust method ologies have higher probability to predict VaRs with too many violations. We illustrate our findings with an empirical exercise in which we estimate VaR for returns of São Paulo stock exchange index, IBOVESPA, during periods of market turmoil. Our results indicate that the robust method based on quantile regression presents the least number of violations.

Being ahead of its time the consumer resistance phenomenon: a comparative case study research

As empresas frequentemente negligenciam o fenômeno da resistência dos consumidores, culminando em investimentos em vão que podem comprometer a sustentabilidade financeira da empresa. Em um mundo onde a novidade é solicitada pelo mercado, as empresas impulsionadas por inovação devem perceber se os consumidores estão preparados para receber uma tecnologia disruptiva. Neste cenário, a difusão tecnológica tornou-se um tema importante de debate entre os pesquisadores. A resistência dos consumidores, no entanto, tem sido negligenciada na literatura. Este estudo analisa as características de inovação percepcionáveis que inibem a massa crítica de consumidores a adotar produtos tecnológicos. Além disso, este estudo complementa a literatura atual, fornecendo resultados empíricos e testando a teoria existente. O projeto de pesquisa tem uma abordagem qualitativa de estudo de caso múltiplo, investigando as características mais relevantes de dois produtos tecnológicos disruptivos que foram rejeitados pela maioria dos consumidores, versus outros dois produtos tecnológicos disruptivos que foram positivamente reconhecidos. Os resultados mostram que a compatibilidade com o estilo de vida do cliente constitui o fator mais importante que levanta barreiras para a adoção.

Work, study, both or neither? time allocation of Brazilian teenagers

Labor force participation among youth is extremely high in Brazil when compared to countries with a similar economic background. In Argentina and Chile labor force participation, among those with 10 to 14 years old, is around 1% while in Brazil this rate is as high as 17 %. For the those between 15 and 19 years old these figures are around 10% in Chile, 15% in Argentina and 53% in Brazil. On the other hand the data on school attendance give a more optimistic picture. The percentage of children, between 10 and 14 years old, enrolled in school increased steadily from 79% to 95% from 1981 to 1998 and with age between 15 and 19, from 46% to 66% in the same period. These figures are close to the ones presented by Chile and Argentina. around 99% among the youngest group and around 70% for the 15 to 19 years old group. The objective of the paper is to understand the determinants of the time allocation decision of the Brazilian youth during the last twenty years. Using a multinomial logit regression we investigate the conditional effect of various micro and macro variables on the time allocation decision for the 1991 to 1998 period. Our main findings are: working and studying became the most likely allocation among the youngest in the poor rural areas and, in general, to study, whether working or not, became less dependent on family background for the youngest group but not for the older.