Question

P Chart	-This is the Sample
Sample	Portion Defective	LCL	Pbar	UCL
0	0.06	0	0.16	0.65
1	0	0	0.16	0.65
2	0.04	0	0.16	0.65
3	0.1	0	0.16	0.65
4	0.06	0	0.16	0.65
5	0.04	0	0.16	0.65
6	0.12	0	0.16	0.65
7	0.1	0	0.16	0.65
8	0.08	0	0.16	0.65
9	0.08	0	0.16	0.65
10	0.1	0	0.16	0.65
11	0.12	0	0.16	0.65
12	0.1	0	0.16	0.65
13	0.12	0	0.16	0.65
14	0.1	0	0.16	0.65
15	0.14	0	0.16	0.65
16	0.08	0	0.16	0.65
17	0.06	0	0.16	0.65
18	0.16	0	0.16	0.65
19	0.12	0	0.16	0.65
20	0.55	0	0.16	0.65
21	0.14	0	0.16	0.65
22	0.2	0	0.16	0.65
23	0.06	0	0.16	0.65
24	0.69	0	0.16	0.65
25	0.005	0	0.16	0.65
26	0.15	0	0.16	0.65
27	0.25	0	0.16	0.65
28	0.36	0	0.16	0.65
29	0.54	0	0.16	0.65
30	0.23	0	0.16	0.65

P Bar	0.1598	SD	0.1628
UCL	0.648
LCL	0

Max	1
Min	0.33
Cpk=	0.33

These is the calculations I was giving and base on that ansewr the below question, no calculation need it

Do we have any data points that are out of control? If so, what are they?

What might be causing these to be out of control?

Do you think the controls are too tight? Why or Why not?

Answer 1

If we plot the points and LCL, CL and UCL.

You can clearly see that the point corresponding to sample 24 with value 0.690 is crossing the upper limit 0.65. Hence The point is outside the limit. Hence the process is out of control. Also, the point corresponding to sample 25,1 and 45 touches the lower limit. These variations are due to non-random causes. which means there are human causes which can be removed are present in the system. We need to find these causes and eliminate those causes. Also if the data corresponds to day point estimate then the process shows the clearly out of control trend. Also, according to defective proportion, we can clearly see that the upper limit is too high. As most of the value falls under the p_bar line. We should decrease the Upper limit.