[pt] A probabilidade de alarme falso, alfa, dos gráficos de controle de processos depende dos seus limites de controle, que, por sua vez, dependem de estimativas dos parâmetros do processo. Esta tese apresenta inicialmente uma revisão dos principais trabalhos sobre o efeito dos erros de estimação dos parâmetros do processo sobre alfa quando se utiliza o gráfico de X e S individualmente e em conjunto. O desempenho dos gráficos é medido através de medidas de desempenho (número médio de amostras até o sinal, taxa de alarme falso, distribuição do número de amostras até o sinal, que, em geral, são variáveis aleatórias, função dos erros de estimação. Pesquisas recentes têm focado nas propriedades da distribuição condicional do número de amostras até o sinal, ou ainda, nas propriedades da distribuição da taxa de alarme-falso condicional. Esta tese adota esta abordagem condicional e analisa o efeito da estimação dos parâmetros do processo no desempenho conjunto dos gráficos de X e S em dois casos: Caso KU (Média conhecida – Variância desconhecida) e Caso UU (Média desconhecida – Variância desconhecida). A quase totalidade dos trabalhos anteriores considerou apenas um gráfico, isoladamente; sobre efeito da estimação dos parâmetros sobre o desempenho conjunto conhecemos apenas um trabalho, sobre gráficos de X e R, mas nenhum sobre gráficos de X e S. Os resultados da análise mostram que o desempenho dos gráficos pode ser muito afetado pela estimação de parâmetros e que o número de amostras iniciais requerido para garantir um desempenho desejado é muito maior que os números tradicionalmente recomendados na literatura normativa de controle estatístico de processo (livros texto e manuais). Esse número é, porém, menor que o máximo entre os números requeridos para os gráficos de X e de S individualmente. Questões a serem investigadas como desdobramento dessa pesquisa são também indicadas nas Considerações Finais e Recomendações. / [en] The false-alarm rate of control charts, alpha, depends on the control limits calculated, which depend, in turn, on the estimated process parameters. This dissertation initially presents a review of the main research articles about the effect of the estimation errors of the process parameters upon alpha when X and S charts are used separately and together. The charts performance is evaluated through performance measures (average run-length, false-alarm rate, run-length distribution, etc), which are, in general, random variables, function of the estimation errors. Recent researches focused on the properties of the conditional run-length, or still (in the case of Shewhart charts) on the properties of the conditional false-alarm rate distribution. This dissertation adopts this conditional approach and investigates the effect of parameter estimation on the joint behavior of X and S charts in two cases: KU Case (Known mean – Unknown variance) and UU Case (Unknown mean - Unknown variance). Almost all previous works considered just only one chart separately – just only one joint performance work is known by the author, one about the effect of the estimation errors of the process parameters upon X e R joint performance. The results show that the charts performance can be severely affected by the parameter estimation and the number of initial samples required to ensure the desirable performance is greater than the numbers of initial samples recommended by traditional statistical process control reference texts (books and manuals). This number is, however, smaller than the maximum between the numbers of samples required by the X and the S charts separately. Additional issues for follow-up research are recommended in the concluding section.

O presente trabalho discute o conceito e natureza jurídica da Cota de Reserva Ambiental (CRA) enquanto instrumento de política ambiental previsto no Novo Código Florestal Brasileiro (Lei Federal nº 12.651/12). O problema de pesquisa se funda em saber se a atual proposta de regulamentação da CRA permitirá a efetividade do instituto. Aspectos teóricos foram discutidos com base em material documental e bibliográfico, recolhidos no âmbito das ciências do direito e da economia. Ao fim, foi realizada pesquisa exploratória sobre o tema, baseada em entrevistas com gestores ambientais, analisadas sob o método dialético-qualitativo. O objetivo, de modo geral, é discutir o atual marco regulatório sobre o tema, de modo criar propostas a sua efetividade. / This paper discusses the concept and legal nature of the Environmental Reserve Quota (CRA) as an environmental policy instrument regulated by the New Brazilian Forest Code (Federal Law nº 12.651/12). The research problem seeks to identify if the current proposal for regulation of the CRA will allow the effectiveness of this institute. Theoretical aspects were discussed on the basis of documentary and bibliographic material collected in the sciences of law and economics. By the end, an exploratory research was conducted on the subject, based on interviews with environmental managers, analyzed from a dialectical qualitative method. The goal, in general, is to discuss the current regulatory framework on the subject with the intention to make proposals to its effectiveness.

The research in this thesis has been undertaken to develop statistical tools for monitoring adverse events in hospitals that adjust for varying patient risk. The studies involved a detailed literature review of risk adjustment scores for patient mortality following cardiac surgery, comparison of institutional performance, the performance of risk adjusted CUSUM schemes for varying risk profiles of the populations being monitored, the effects of uncertainty in the estimates of expected probabilities of mortality on performance of risk adjusted CUSUM schemes, and the instability of the estimated average run lengths of risk adjusted CUSUM schemes found using the Markov chain approach. The literature review of cardiac surgical risk found that the number of risk factors in a risk model and its discriminating ability were independent, the risk factors could be classified into their "dimensions of risk", and a risk score could not be generalized to populations remote from its developmental database if accurate predictions of patients' probabilities of mortality were required. The conclusions were that an institution could use an "off the shelf" risk score, provided it was recalibrated, or it could construct a customized risk score with risk factors that provide at least one measure for each dimension of risk. The use of report cards to publish adverse outcomes as a tool for quality improvement has been criticized in the medical literature. An analysis of the report cards for cardiac surgery in New York State showed that the institutions' outcome rates appeared overdispersed compared to the model used to construct confidence intervals, and the uncertainty associated with the estimation of institutions' out come rates could be mitigated with trend analysis. A second analysis of the mortality of patients admitted to coronary care units demonstrated the use of notched box plots, fixed and random effect models, and risk adjusted CUSUM schemes as tools to identify outlying hospitals. An important finding from the literature review was that the primary reason for publication of outcomes is to ensure that health care institutions are accountable for the services they provide. A detailed review of the risk adjusted CUSUM scheme was undertaken and the use of average run lengths (ARLs) to assess the scheme, as the risk profile of the population being monitored changes, was justified. The ARLs for in-control and out-of-control processes were found to increase markedly as the average outcome rate of the patient population decreased towards zero. A modification of the risk adjusted CUSUM scheme, where the step size for in-control to out-of-control outcome probabilities were constrained to no less than 0.05, was proposed. The ARLs of this "minimum effect" CUSUM scheme were found to be stable. The previous assessment of the risk adjusted CUSUM scheme assumed that the predicted probability of a patient's mortality is known. A study of its performance, where the estimates of the expected probability of patient mortality were uncertain, showed that uncertainty at the patient level did not affect the performance of the CUSUM schemes, provided that the risk score was well calibrated. Uncertainty in the calibration of the risk model appeared to cause considerable variation in the ARL performance measures. The ARLs of the risk adjusted CUSUM schemes were approximated using simulation because the approximation method using the Markov chain property of CUSUMs, as proposed by Steiner et al. (2000), gave unstable results. The cause of the instability was the method of computing the Markov chain transition probabilities, where probability is concentrated at the midpoint of its Markov state. If probability was assumed to be uniformly distributed over each Markov state, the ARLs were stabilized, provided that the scores for the patients' risk of adverse outcomes were discrete and finite.

O presente trabalho discute o conceito e natureza jurídica da Cota de Reserva Ambiental (CRA) enquanto instrumento de política ambiental previsto no Novo Código Florestal Brasileiro (Lei Federal nº 12.651/12). O problema de pesquisa se funda em saber se a atual proposta de regulamentação da CRA permitirá a efetividade do instituto. Aspectos teóricos foram discutidos com base em material documental e bibliográfico, recolhidos no âmbito das ciências do direito e da economia. Ao fim, foi realizada pesquisa exploratória sobre o tema, baseada em entrevistas com gestores ambientais, analisadas sob o método dialético-qualitativo. O objetivo, de modo geral, é discutir o atual marco regulatório sobre o tema, de modo criar propostas a sua efetividade. / This paper discusses the concept and legal nature of the Environmental Reserve Quota (CRA) as an environmental policy instrument regulated by the New Brazilian Forest Code (Federal Law nº 12.651/12). The research problem seeks to identify if the current proposal for regulation of the CRA will allow the effectiveness of this institute. Theoretical aspects were discussed on the basis of documentary and bibliographic material collected in the sciences of law and economics. By the end, an exploratory research was conducted on the subject, based on interviews with environmental managers, analyzed from a dialectical qualitative method. The goal, in general, is to discuss the current regulatory framework on the subject with the intention to make proposals to its effectiveness.