Economic design of two-stage (X)over-bar charts: the Markov chain approach

When the (X) over bar chart is in use, samples are regularly taken from the process, and their means are plotted on the chart. In some cases, it is too expensive to obtain the X values, but not the values of a correlated variable Y. This paper presents a model for the economic design of a two-stage control chart, that is. a control chart based on both performance (X) and surrogate (Y) variables. The process is monitored by the surrogate variable until it signals an out-of-control behavior, and then a switch is made to the (X) over bar chart. The (X) over bar chart is built with central, warning. and action regions. If an X sample mean falls in the central region, the process surveillance returns to the (Y) over bar chart. Otherwise. The process remains under the (X) over bar chart's surveillance until an (X) over bar sample mean falls outside the control limits. The search for an assignable cause is undertaken when the performance variable signals an out-of-control behavior. In this way, the two variables, are used in an alternating fashion. The assumption of an exponential distribution to describe the length of time the process remains in control allows the application of the Markov chain approach for developing the cost function. A study is performed to examine the economic advantages of using performance and surrogate variables. (C) 2003 Elsevier B.V. All rights reserved.

Economic growth and the quality labour market of jobs created: a Brazilian case and some implications to Latin America

An outcome of economic growth is increased employment, but this should not be the only measure to assess a country's labour market, it is also important to verify whether the jobs created are considered good jobs. Thus, this study analyses the Brazilian labour market from 2000 to 2009, in terms of the quantity and quality of jobs generated in this period. To this end, a descriptive analysis was performed, in addition to an evaluation using econometrics and the data envelopment analysis (DEA) technique. The results of the research indicated that the Brazilian labour market is growing in terms of its quality.