W8 _Said Alamri_ Control Chart (i.e. Run Chart)

1. Problem Recognition

Car tyres factory is designed to produce 900 tyre per day. Although the number of tyres rejected by quality control section due to manufacturing defect are recorded in daily production for a month of August around 340 tyres. The QC department wants to draw a control chart to present the values to management. After that the management can take action to purchase tyres recycling machine. And determine the machine capacity that will be purchased.

2. Development the Feasible Alternative

Quality control department recorded the items rejected for the month of August 2014. Control chart will be presented to management for the quantity rejected in a month in order to support their proposal to purchase recycling machine.

3. Development of the Outcome for Alternative

The quantity rejected recorded in table-1. The mean and Upper/Lower Control Limit are calculated as well.

Table-1 Items rejected in the month of August 2014

Table-1 Items rejected in the month of August 2014

4. Selection of Criteria

Recycling machine capacity will be purchase based on the upper control limit calculated for a month.

5. Analysis and Comparison of the Alternatives

The Run chart (control chart) was generated from the data collected in daily production report and shown below in Figure-1. The upper control limit calculated to be 22 Items for a month.

Figure-1 Control chart generated from data collected in August2014

Figure-1 Control chart generated from data collected in August2014

6. Selection of the Preferred Alternative

It can be observed from control chart that the average items rejected is 12 items per day and between 22-1 items for a month. The recycling machine which will be purchased should have a capacity to recycle 22 tyers per day.

7. Performance Monitoring and the Post Evaluation of Result

Production department will monitor the daily production and will initiate return on investment report for recycling machine.

8. References:

  1. Bassard, Michael & Riter, Diane (2010). The Memory Jogger 2nd Edition, Canada, GOAL/QPC
  2. A Guide to Control Charts, retrieved on 8th of August2014 http://www.isixsigma.com/tools-templates/control-charts/a-guide-to-control-charts/
  3. What are Variables Control Charts?, retrieved on 8th of August2014 http://www.itl.nist.gov/div898/handbook/pmc/section3/pmc32.htm

One thought on “W8 _Said Alamri_ Control Chart (i.e. Run Chart)

  1. Hi Said, is this a REAL case study from your day to day working world or is this a case study you picked up from one of your references?

    The reason I ask is this is NOT an example I would expect to see in a PROJECT management class……

    Where we normally use run charts is when we are looking at cost data or schedule (duration) data. Before we can run a PERT analysis, we must FIRST eliminate the outliers. How do we do this? By putting together a run chart and throwing out any values which fall outside the upper or lower control limits. IF we fail to do this, then it can seriously impact our PERT calculations…… (If I recall, didn’t that happen during our face to face session? As I recall when we were estimating how long it would take to write a paper there were a couple of data points which were so far out of line to be ridiculous numbers?)

    Anyway, even though I question the case study the work you did on it was excellent. One additional suggestion however, Turn to page 63 in your Memory Jogger 2 and maybe for your next blog you can see if the process is out of control for an INTERNAL (process related) problem? Use the same data but this time break it into three bands above and below the mean and see if you get any patterns that match those shown on page 63. (HINT: Pay special attention to 2C and 2D as almost 100% you will see those on your PMP exam)

    Keep up the good work and great to see you catching up….

    Dr. PDG, Jakarta

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