Question

The data in below table lists country code and the order to remittance (OTR) time for hardware / software installations for the last 76 installations (from first to last). OTR is the time it takes from an order being placed until the system is installed and we receive payment (remittance). Because this company does business internationally, it also notes the country of installation using a country code. This code is listed in the first column.

Table: Country Code and OTR Cycle Time for Software Systems Installation

Country Code	Cycle Time	Country Code	Cycle Time
1	20	5	29
1	24	6	40
1	46	7	157
1	26	8	19
14	38	5	24
1	15	1	81
1	15	7	53
17	23	7	26
1	31	1	28
1	31	1	34
6	64	1	34
5	29	7	50
5	44	1	52
1	32	1	19
1	15	1	44
7	11	14	150
7	14	7	29
1	89	17	23
17	41	6	79
7	41	17	13
1	36	6	32
8	43	7	61
17	21	8	42
8	28	8	46
7	18	7	88
8	47	14	24
6	26	7	7
6	47	1	33
5	9	5	129
7	42	17	41
5	5	17	43
6	27	14	42
6	27	14	42
1	33	7	53
7	44	7	53
1	21	7	48
1	22	5	21
1	50	1	19

Use the date in table above and answer the following questions in the space provided below:

1. Does the OTR time appear to be stable? Why or why not?
2. If you were to use a control chart to evaluate stability, which chart would you use? Why?
3. What can you learn about the distribution of the installation process?
4. Does it appear that the country has an impact on installation time? Why or why not?

Answer 1

Number of samples	76
	Defects per sample
Upper Control Limit, UCL	58.371
Center	39.513
Lower Control Limit, LCL	20.655

The c-chart is used.

The control chart is:

The process is out of control.

No, the country has no impact on installation time.