Question

For the following data set, create a control chart. Remember to label your chart. Does is appear that the process is out of control? Why or why not?

The following data set shows the amount filled in soda cans for three different samples at different time periods.

time	sample 1	sample 2	sample 3
10:00 AM	12.01	12.03	12
12:00 PM	11.99	12.01	11.96
2:00 PM	12	11.96	12.04
4:00 PM	11.98	12	11.97
6:00 PM	12.01	11.99	12.01
8:00 PM	11.97	12.02	12.02

Answer 1

For x bar and R chart we need to find sample averages and sample ranges from the given data set

Let's use excel for calculation

X bar Chart

Central line = =11.99833

Upper control limit = = 11 .99833 + 1.023*0.04333 = 12. 04266

Lower control limit = = 11 .99833 - 1.023*0.04333 = 11.954

Since all the sample means lies within Upper control limit and lower control limit , the X - bar chart is in statistical control.

Let's find R contro limits

Central line = = 0.04333

Upper control limit = ...For n= 3, D₄ = 2.574

Lower control limit = D₃ * = 0 ... For n = 3 , D₃ = 0

Since all the sample ranges lies between 0.11154 and 0 the range that is spread is also in statistical control.

The process is in statistical control for both average and spread.