Summary Two different medical measurement methods, which usually do not produce exactly the same results, are used to analyse the serum levels of folic acid in a blood sample. We assess the (dis)agreement of the available data in order to replace the old method (the reference method, which involves a lot of human intervention) with the new one (which uses mostly machines), without causing problems in clinical interpretation. The 95% limits of agreement are estimated, before and after a logarithmic transformation, and an appropriate use of regression and a nonparametric approach are also considered. The application of these different statistical techniques is very useful and easily interpreted by medical researchers, but the results obtained do not provide confidence that the new method can be used in place of the old one for clinical purposes.

In European countries, namely in Portugal, it is common to hear some people mentioning that they are exposed to excessive and continuous psychosocial stressors at work. This is increasing in diverse activity sectors, such as, the Services sector. A representative sample was collected from a Portuguese Services' organization, by applying a survey (internationally validated), which variables were measured in five ordered categories in Likert-type scale. A multinomial logistic regression model is used to estimate the probability of each category of the dependent variable general health perception where, among other independent variables, burnout appear as statistically significant.

Acidity is one of the most important variables in the quality analysis and characterization of olive oil. During the industrial production we use individuals and moving range charts to monitor this variable, which is not always normal distributed. After a brief exploratory data analysis, where we use the bootstrap method, we construct control charts, before and after a Box-Cox transformation, and compare their robustness and performance.

The production of gypsum (marketed if it accomplishes the required specifications) occurs during the process of flue gas desulphurization in a Portuguese Coal Thermoelectric Central. Important variables in this process are statistically analyzed in the chemical laboratory and quality control charts are implemented to monitor the entire process. In this study individuals and moving range charts of the variable "density of gypsum slurry" are compared with the "more efficient" ones obtained after a Box-Cox transformation. This transformation is used to normalize the data, because its observations come from non-normal models-where classical control charts are considered less appropriate, since they usually exhibit rates of false alarms different from what would be expected. Although it is important to consider different statistical approaches for quality control charts, during the monitoring of an industrial process, in this case study the achieved results lead us, essentially, to similar conclusions.