WK 7_Mahfoodha_ SPC analysis for Takatuf Team blog posting project

  1. Problem definition.

In the previous Blog a statistical analysis was conducted on the blog posting data in order to be validated measured whether the process was in- control or not. The outcome of the analysis proved that the data was valid. However, to further the investigation on this topic a statistical analysis will be conducted on the whole Takatuf- PMI- 2014 teams’ data. As illustrated in the previous blog this exercise is imported, as it provides a tool to measure the current status of the project and allows the team to monitor, control and improve the performance of the process for the rest duration of the project.

Hence, the topic of this blog will be analyzing statistically the process of blog posting for the Takatuf PMI team using SPC methods and explore manners of improvements.

  1. Identify the feasible alternative.

Statistical Process Control (SPC) is tool to recognize the source of variation in a process. It is a tool that used in the industry to monitor the process variation over time, and identifies the common causes for this variation.

Following the process identified in the previous blog, in order to implement SPC the following steps should be taken [1]:

  1. Identifying the measurement method
  2. Qualifying the measurement system
  3. Collect the data and initiate the SPC Charting
  4. Reaction plan development and documentation
  5. Include chart to the control plan
  6. Calculate the control limits
  7. Assess the control process
  8. Analyze the data to identify root cause and correct
  9. Design and implement actions to improve process capability
  10. Calculate CP and CPK and compare to Benchmark
  11.  Monitor and focus efforts on next highest priority.


For the purpose of this paper X and R charts will be used to analyze the SPC data from the team blog posting project. This is mainly done to detect any variation on the process of the blog posting development as well as controlling the process and probably improve it if required.

As illustrated previously in the week 6 blog, that there are many types of control charts that are being used in the industry. The type of charts depends on the type of the data as following:

  • Variable data: measured and plotted on a continuous scale this includes time, temperature cost and figures
  • Attribute data : measured on discrete events such as shipping errors and  percentage of waste

3. Selection of criteria 

As the data collected and measured for the blog posting is time the type of control chart to be used is Average X and Range R chart with sample sizes >10.

4. Development of the outcome for alternative.

The team consisted of 25 members where blog posting was a weekly deliverable. The project is currently at its 7th week; therefore, the analysis will be conducted on 6 weeks of collected data

To develop an analysis for the team blog posting, the following were taken into consideration:

  • Each individual or member of the team will be considered as Subgroup
  • The 6 weeks will be considered the no. of the data collected for each subgroup
  • The quality measure here, will be time


Blog posting Data

For a variable data such as the described the following data were developed to produce a control chart with± 3x Deviation.

Xbar chart data

The above data was then translated to the following chart:


xbar chart5. Analysis of the alternatives:

To analyze the data shown in the above chart, A further step was taken which included producing ±1 Sigma & ±2 Sigma.  As shown in the above chart, it is clear that the blog posting process is out of control. However, how much “out of control” this process is? This can be analyzed by dividing the chart into zones. the following image illustrates how to determine a process being out of control using the zones


Taking the above into consideration the following chart was then produced:

control chart Zones

As illustrated in the above chart 4 points are above the upper control limit. Also 7 points are between -2 Sigma and the lower control limit which is a clear indication that this process is out of control.  6 points can also be seen in the zone between -1 sigma and -2 sigma.

Although the location of the Central Line (Mean) sits around 0.9Hrs and meets the specification of the project, the data around the mean line illustrates high variation that could only be interpreted as the team Blog posting is out of control.  These variations are a result of special causes that could be due to

  • measurement in-accuracy (i.e how honest is the time reported by each member to conduct the weekly blog posting),
  • different methods used to produce the blog from a member to the other,
  • is the blog posting process affected by external factors such as work, family issues?
  • The learning curves from one individual to the other differs
  • Variation in individuals capabilities
  • Change in Environment. The month of the Ramadan could be a cause for it too.

6. Selection of the preferred alternatives

The conclusion of the above analysis indicates that the team blog posting is an out of control process. This requires a route cause analysis to be conducted to determine the reasons behind the variations and tackle those issues. This should be conducted as team excersise as it involves all members of the program. An initial analysis of the team performance to be conducted used as basis for the team workshop to analyze where the variations are coming from.


7. Performance Monitoring and the Post Evaluation of Result.

To bring the blog posting process status to “in-control” position, a continuous updating to the SPC of this project to be conducted. As well as tackling special causes for the variation that occurred in the previous weeks.


 8. References:

1. InfinityQS (2014). What is Statistical Process Control (SPC)?. [ONLINE] Available at: http://www.infinityqs.com/resources/what-is-spc. [Last Accessed July 14, 2014].
2. Syque Quality (). Calculation for Average and Range Control Charts. [ONLINE] Available at: http://www.syque.co.uk/quality_tools/toolbook/Control/do_avg_range_calc.htm. [Last Accessed July 17, 2014]
3. Edgell R (2014). Statistical Process Control Explained. [ONLINE] Available at: http://www.winspc.com/what-is-spc/statistical-process-control-explained. [Last Accessed July 14, 2014].
4. Brassard M, Ritter D, (2010). Memory Jogger 2. 2nd ed. USA: GOAL/QPC.
5. LSS Money Belt. (2010, December 21). SPC Simplified – Control Charts [Video file]. Retrieved from http://www.youtube.com/watch?v=RYMIcEOh5M8


One thought on “WK 7_Mahfoodha_ SPC analysis for Takatuf Team blog posting project

  1. AWESOME posting Ms. Mahfoodah!!!! Very “real” case study and your analysis was just about perfect.

    The only “mistake” you made was you missed one additional step that you should have done but you can pick up in your W8 blog. Because you have 4 readings which fall OUTSIDE the upper control limits, you need to THROW OUT those readings and not count them in the mean. This will change your mean and should also narrow your bands a little bit.

    Bottom line- finish up this one last step as the basis for your W8 blog and see whether the process is still out of control or not.

    Dr. PDG, Jakarta

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