Comparar métodos
Examine os métodos selecionados lado a lado; as linhas que diferem ficam destacadas.
| Gráficos de Controle por Atributos (p, np, c, u)× | Gráfico de Controle de Média Móvel Exponencialmente Ponderada (EWMA)× | |
|---|---|---|
| Área | Estatística | Estatística |
| Família | Process / pipeline | Process / pipeline |
| Ano de origem≠ | 1931 | 1959 |
| Autor original≠ | Walter A. Shewhart | S. W. Roberts |
| Tipo≠ | Statistical process control charts for count/proportion data | Statistical process control chart for small shifts |
| Fonte seminal≠ | Shewhart, W. A. (1931). Economic Control of Quality of Manufactured Product. D. Van Nostrand Company. ISBN: 978-0-87389-076-2 | Roberts, S. W. (1959). Control chart tests based on geometric moving averages. Technometrics, 1(3), 239–250. DOI ↗ |
| Outros nomes≠ | p-chart, np-chart, c-chart, u-chart | exponentially weighted moving average chart, EWMA control chart, geometric moving average chart, EWMA kontrol kartı |
| Relacionados≠ | 4 | 3 |
| Resumo≠ | Attributes control charts extend Shewhart's framework to count and proportion data — quality characteristics that are classified rather than measured. The p- and np-charts monitor the proportion or number of defective items using the binomial distribution, while the c- and u-charts monitor the number of defects per unit using the Poisson distribution. They are the standard statistical-process-control tools when inspection yields pass/fail or defect counts rather than continuous measurements. | The exponentially weighted moving average (EWMA) control chart, introduced by S. W. Roberts in 1959, monitors a process using a weighted average that gives the most recent observation the greatest weight while letting older observations fade geometrically. Like CUSUM, this memory makes it highly effective at detecting small, sustained shifts in the process mean, with a single smoothing parameter λ controlling how much past information the chart retains. |
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