# Question: The waiting time for treatment in a minute clinic located in

The waiting time for treatment in a “minute-clinic” located in a drugstore is monitored using control charts for individuals and the moving range. Table 6E.24 contains 30 successive measurements on waiting time.

(a) Set up individual and moving range control charts using this data.

(b) Plot these observations on the charts constructed in part (a). Interpret the results. Does the process seem to be in statistical control?

(c) Plot the waiting time data on a normal probability plot. Is it reasonable to assume normality for these data? Wouldn’t a variable like waiting time often tend to have a distribution with a long tail (skewed) to the right? Why?

(a) Set up individual and moving range control charts using this data.

(b) Plot these observations on the charts constructed in part (a). Interpret the results. Does the process seem to be in statistical control?

(c) Plot the waiting time data on a normal probability plot. Is it reasonable to assume normality for these data? Wouldn’t a variable like waiting time often tend to have a distribution with a long tail (skewed) to the right? Why?

**View Solution:**## Answer to relevant Questions

The waiting time data in Exercise 6.66 may not be normally distributed. Transform these data using a natural log transformation. Plot the transformed data on a normal probability plot and discuss your findings. Set up ...The uniformity of a silicon wafer following an etching process is determined by measuring the layer thickness at several locations and expressing uniformity as the range of the thicknesses. Table 6E.29 presents uniformity ...The vane heights for 20 of the castings from Figure 6.25 are shown in table 6E.32. Construct the “between/within” control charts for these process data using a range chart to monitor the within-castings vane height. ...Based on the data in Table 7E.8 if an np chart is to be established, what would you recommend as the center line and control limits? Assume that n = 500. In designing a fraction nonconforming chart with center line at p = 0.20 and three-sigma control limits, what is the sample size required to yield a positive lower control limit? What is the value of n necessary to give a ...Post your question