VSSI (X)over-bar charts with sampling at fixed times
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Data
1998-01-01
Autores
Costa, AFB
Título da Revista
ISSN da Revista
Título de Volume
Editor
Marcel Dekker Inc
Resumo
A standard (X) over bar chart for controlling the process mean takes samples of size no at specified, equally-spaced, fixed-time points. This article proposes a modification of the standard (X) over bar chart that allows one to take additional samples, bigger than no, between these fixed times. The additional samples are taken from the process when there is evidence that the process mean moved from target. Following the notation proposed by Reynolds (1996a) and Costs (1997) we shortly call the proposed (X) over bar chart as VSSIFT (X) over bar chart: where VSSIFT means variable sample size and sampling intervals with fixed times. The (X) over bar chart with the VSSIFT feature is easier to be administered than a standard VSSI (X) over bar chart that is not constrained to sample at the specified fixed times. The performances of the charts in detecting process mean shifts are comparable.
Descrição
Palavras-chave
average time to signal, (X)over-bar control charts, statistical process control, variable sample size, variable sampling interval
Como citar
Communications In Statistics-theory and Methods. New York: Marcel Dekker Inc., v. 27, n. 11, p. 2853-2869, 1998.