A courier company conducted a brainstorming session amongst drivers to ascertain the reasons why it was unable to deliver items to households, always right first time. One major reason suggested by drivers during the session was "customer not at home" when the driver arrived. If there were no specific instructions from the customer, for example "leave on door step" or "leave behind garbage bins", drivers were generally reluctant to leave the item unattended. In such cases, items were returned to the company's warehouse, the customer contacted and an alternative time arranged. For some customers, it took several attempts before an item was delivered successfully. The result was a poor customer experience and significant rework costs incurred by the company.
The company decided to measure the size of the issue, which it classified as the defect "customer not at home". It examined Monday to Friday data from 3rdAugust 2009 to 1stth October 2009 with an intention of developing a baseline from which to consider improvement. It sampled its Monday to Friday deliveries, each day taking 500 random delivery attempts and recording whether the driver was unable to deliver due to "customer not at home". See the data file. There was no reason to believe that Monday was systematically better or worse than Tuesday or Tuesday was systematically better or worse than Wednesday etc.
(a) Summarise the baseline performance of deliveries with respect to the defect "customer not at home". Do not remove any data.
Group Assignment (2010)
Having established the baseline, the company set about asking the courier drivers for improvement suggestions. It was agreed that a solution called "Double SMS" be trialled.
The customer would be sent an SMS advising on possible delivery time windows soon after the item was received in the company's warehouse. The customer would then select a preferred delivery window. A few hours before the scheduled delivery, a second SMS would be sent, asking the customer for a confirmation that he/she would be at home during the agreed delivery time window. If the customer advised he/she would not be at home, the customer would be offered an alternative delivery window.
Trials with the "Double SMS" solution began on 2nd October and continued until 11th November when enough data points had been gathered to consider the solution successful and sustainable.
(b) Summarise the performance of the new process. Do not remove any data.
(c) Discuss and demonstrate using a single control chart the extent of the improvement that has occurred from the old process to the new process. Do not remove any data.
(d) Recommend what next steps you would take with the new process. You are not required to undertake these steps.