Operations Management: Processes and Supply Chains, 12th Edition

Key Equations

Time Study Method

1. Required sample size in a time study: $n={\left[\left(\frac{z}{p}\right)\left(\frac{\sigma }{\overline{t}}\right)\right]}^2$

2. Normal time for a work element: $\text{NT}=\overline{t}(F)(\text{RF})$

3. Normal time for the cycle: $\text{NTC}\text{=}\Sigma \text{NT}$

4. Standard time: $\text{ST}=\text{NTC}(1+A)$

Work Sampling Method

5. Required sample size in a work sampling study: $n={\left(\frac{z}{e}\right)}^2\widehat{p}(1-\widehat{p})$