PEI Potato Purveyors

Throughout the year in 2018, Angus MacDonald had been receiving random complaints from various customers. Angus is the operations manager at PEI Potato Purveyors Inc. and the complaints he received surrounded the fact that the quantities of product delivered were inconsistently deviating from the amounts specified on the packaging. This would require Angus to fully investigate this matter.

Angus ordered the supervisors to undertake a random sample weight measurement of 50 containers, each of which historically held 50 kilograms of potatoes, with an acceptable standard deviation of 1.2 kilograms. Upon closer examination, Angus discovered that the potato containers in this random sample weighed on average 47.51 kilograms, well outside of the acceptable standard deviation. Angus was deeply concerned for several reasons. Why did he receive only random and not consistent complaints? Did no one notice or was this an inconsistent problem? Why had the weight changed over the years while using the same container?

	Average Weight Kilograms	Range		Average Weight Kilograms	Range
Time	Smallest	Largest	Time	Smallest	Largest
6:00 a.m.	49.6	48.7	50.7	6:00	46.8	41.0	51.2
7:00	50.2	49.1	51.2	7:00	50.0	46.2	51.7
8:00	50.6	49.6	51.4	8:00	47.4	44.0	48.7
9:00	50.8	50.2	51.8	9:00	47.0	44.2	48.9
10:00	49.9	49.2	52.3	10:00	47.2	46.6	50.2
11:00	50.3	48.6	51.7	11:00	48.6	47.0	50.0
12 Noon	48.6	46.2	50.4	12 Midnight	49.8	48.2	50.4
1:00 p.m.	49.0	46.4	50.0	1:00 a.m.	49.6	48.4	51.7
2:00	49.0	46.0	50.6	2:00	50.0	49.0	52.2
3:00	49.8	48.2	50.8	3:00	50.0	49.2	50.0
4:00	50.3	49.2	52.7	4:00	47.2	46.3	50.5
5:00	51.4	50.0	55.3	5:00	47.0	44.1	49.7
6:00	51.6	49.2	54.7	6:00	48.4	45.0	49.0
7:00	51.8	50.0	55.6	7:00	48.8	44.8	49.7
8:00	51.0	48.6	53.2	8:00	49.6	48.0	51.8
9:00	50.5	49.4	52.4	9:00	50.0	48.1	52.7
10:00	49.2	46.1	50.7	10:00	51.0	48.1	55.2
11:00	49.0	46.3	50.8	11:00	50.4	49.5	54.1
12 Midnight	48.4	45.4	50.2	12 Noon	50.0	48.7	50.9
1:00 a.m.	47.6	44.3	49.7	1:00 p.m.	48.9	47.6	51.2
2:00	47.4	44.1	49.6	2:00	49.8	48.4	51.0
3:00	48.2	45.2	49.0	3:00	49.8	48.8	50.8
4:00	48.0	45.5	49.1	4:00	50.0	49.1	50.6
5:00	48.4	47.1	49.6	5:00	47.8	45.2	51.2
6:00	48.6	47.4	52.0	6:00	46.4	44.0	49.7
7:00	50.0	49.2	52.2	7:00	46.4	44.4	50.0
8:00	49.8	49.0	52.4	8:00	47.2	46.6	48.9
9:00	50.3	49.4	51.7	9:00	48.4	47.2	49.5
10:00	50.2	49.6	51.8	10:00	49.2	48.1	50.7
11:00	50.0	49.0	52.3	11:00	48.4	47.0	50.8
12 Noon	50.0	48.8	52.4	12 Midnight	47.2	46.4	49.2
1:00 p.m.	50.1	49.4	53.6	1:00 a.m.	47.4	46.8	49.0
2:00	49.7	48.6	51.0	2:00	48.8	47.2	51.4
3:00	48.4	47.2	51.7	3:00	49.6	49.0	50.6
4:00	47.2	45.3	50.9	4:00	51.0	50.5	51.5
5:00	46.8	44.1	49.0	5:00	50.5	50.0	51.9

Further investigation informed Angus of several contributing factors. The PEI Potato Purveyors's typical customer would be a food processing company that makes large quantities of French fries, mashed potatoes, hash browns, etc. The container that is used is too heavy to lift and is normally loaded and unloaded by forklift, and in some cases, the entire quantity is dumped into a processing machine. Some machines would process 50 kilograms of potatoes at one time. If the input was short on quantity, so too would the output be, and this would be noticeable to the food processing firm. Angus discovered that the majority of complaints were generated by firms with this type of equipment, and he immediately ordered a credit for those that brought this situation to his attention.

But Angus still had to uncover the root cause and rectify it. What was different now than before that could affect the weight? It turned out that although they were using the same containers, they were using a different lid that dipped into the container somewhat. In order to fit the lid properly, employees would remove several potatoes from the container rather than push down and damage them. Also, it was discovered that they had a new supplier of potatoes added to their list, and this farm produced a new type of potato that was large and irregular in shape. This caused more air space in the container, thus less weight. Ultimately, a new container lid that resembled the original style would be required, and a new sorting mechanism for the large irregular-shaped potatoes.

Angus wanted to determine if different shifts in the plant were dealing with these issues in a different way and arranged for six random weight measurements per hour to be taken throughout the day.

Discussion Questions/ the sample charts are given in images, at the start of the question

1. Comment on what you perceive as the contributing factors to the challenges with the weight of the containers.

2. What policies, procedures, and protocols would you implement to correct this quality issue?

3. Make a control chart with the given information.