Many Six Sigma practitioners use “Student’s” independent two-sample t-test when investigating differences in means. This type of test is based upon drawing random samples from two independent normal (Gaussian) distributions. Often, however, the assumption of normality and/or random sampling is violated. This article discusses when and why the two-sample t-test may be considered robust to these ...

Power is defined as the probability of correctly detecting an effect. It is often noted , where the converse, ̄ is the probability of a type-II error (not rejecting H0 when there is an effect). When planning a new experiment, it is generally recommended to have a power of at least .80. Suppose that your design has very little power and suppose further that you found a significant effect. Since y...

in the use of peer group data to assess individual, typical or best practice performance, the effective detection of outliers is critical for achieving useful results. in these ‘‘deterministic’’ frontier models, statistical theory is now mostly available. this paper deals with the statistical pared sample method and its capability of detecting outliers in data envelopment analysis. in the prese...

É proibida a reprodução parcial ou integral do conteúdo deste documento por qualquer meio de distribuição, digital ou im-presso, sem a expressa autorização do Insper ou de seu autor. A reprodução para fins didáticos é permitida observando-sea citação completa do documento Abstract This paper examines a set of inflation-targeting countries and presents evidence on the attitude of policymakers to...