NP-Chart

368. NP-Chart

Number of defective items (constant sample size)

\begin{matrix} {UCL}_{𝑛 𝑝} = 𝑛 \bar{𝑝} + 3 \sqrt{𝑛 \bar{𝑝} (1 - \bar{𝑝})} \\ {LCL}_{𝑛 𝑝} = 𝑛 \bar{𝑝} - 3 \sqrt{𝑛 \bar{𝑝} (1 - \bar{𝑝})} \end{matrix}

Where:

\begin{aligned} \bar{𝑝} & = \frac{1}{𝑘} \sum_{𝑖 = 1}^{𝑘} \frac{𝑑_{𝑖}}{𝑛} \\ = \frac{\sum_{𝑖 = 1}^{𝑘} 𝑑_{𝑖}}{𝑛 \cdot 𝑘} \end{aligned}