iSixSigma

Savage

Activity

  • Capability analysis is an essential tool for statistical process control (SPC) and process improvement, applicable to a variety of environments from hospitals and labs to assembly and manufacturing. The formula […]

  • Here in Dayton, Ohio, this individual might be a resource to help you: Rusty Clifford, West Carrollton City Schools Superintendent. http://www.westcarrolltonschools.com 8 years, 10 months ago

  • I could be mistaken, but I think Craig was simply requesting a new category to be added. I don’t think he was soliciting opinions on how easy problems are to solve in a particular industries. But it is good to know that there are other experts available to help. 8 years, 10 months ago

  • Before software was so commonly used, a “rule of thumb” was to not change the limits unless the percent change in the denominator changed by more than 25% from the average denominator.

    Some people make the limits flat so that they are easy to read. The problem with flat limits is that you may make more errors with interpreting the chart. (Not…[Read more]

  • If you are familiar with the concept of NDC using study parameters, this is the same requirement using specifications. The calculation is: ndc = 1.41* PV/GRR The desired minimum of ndc > 5 if inverted and changed to a percent is 20%. Dividing 5.15 * GRR by the Specification Spread results in the percent the measurement error uses of the the…[Read more]

  • To answer the original question, Pp and Ppk would typically be defined as n/a since they can not be calculated when the standard deviation of the individual values = 0. (You can not use 0 as the denominator and get a number. Your calculator would show this as an error and Excel would list the answer as “#DIV/0!) 9 years, 11 months ago

  • I asked Minitab directly a couple years ago and there isn’t a direct way to do it.  You have to tile the two different graphs.  You can then position them next to each other. 
    Good luck. 10 years, 9 months ago

  • There are two types of rare event control charts that are gaining attention. If you find that a traditional control chart is not working for you, you may consider using a g-chart or t-chart. The t-chart is similar to the g-chart except the time between a rare event is recorded. I.e. the days (or weeks or …) passed since the last on-the-job…[Read more]

  • Lorax,
    I would like a copy of your simulation. It would be greatly appreciated.
    [email protected]

  • Savage replied to the topic Minitab in the forum General 11 years, 9 months ago

    Not sure you are still stuck on this, but you can import the full dataset from Excel by going to File , Open Worksheet.  I think this is an error in the software. 

  • Thanks Andy/newbie,
    We did have issues with the measurement device initially, but we resolved those problems and moved forward with the study.
    I have already looked at the data on a multi-vari and within piece variation is greatest. 
    My heartburn is in creating subgroups after the data has already been collected.  I have a list of 75 data p…[Read more]

  • In short I was trying to communicate (very poorly, I suppose) that one technique for dealing with non-normal data is to follow the AIAG manual. 
    One of their techniques calculates the std. dev. the regular way. However, when it comes time to calculate a capability index such as Pp or Ppk, a different technique is used. As I think I remember, the…[Read more]

  • And your reply is supposed to help other readers?
    I made a post to educate at least one person, and if this worked, I am happy. If you do understand my post, you can either ask for clarification or zip it. Didn’t your mother tell you “If you do not have anything nice to say, then don’t say it at all.”

  • If data is not bell-shaped, I would use the same sigma that comes from Excel when you calculate the standard deviation. i.e. =STDEV

    This is sometimes referred to as the standard deviation of the individual values. Anyhow, back to your question. Use this sigma and then calculate your index, Ppk, using a technique like that illustrated on page…[Read more]

  • Savage replied to the topic Belt question in the forum General 12 years ago

    Here’s a nice six sigma belt resource you might find helpful.

  • Savage replied to the topic CP in minitab in the forum General 12 years, 1 month ago

    Re-submitted by Matt – noticed some typos!
    Everything is a process – regardless of whether its manufacturing or transactional and therefore Lean can be applied to all processes. You really need to understand your TAKT time first and then establish baselines (where did the 10 days come from? what is your customer demand rate? you processed…[Read more]

  • Savage replied to the topic CP in minitab in the forum General 12 years, 1 month ago

    everything is a process – regardless of whether its manufacturing or transactional and therefore lean can be applied to all processes. You really need to understand your takt time first and then establish baselines (where did the 10 days come drom – what is your customer demand rate, you processed 250,000 requests from last year however how many…[Read more]

  • Savage replied to the topic X-Bar R Charts in the forum General 12 years, 5 months ago

    I generally agree with Michael.
    One note is that you will never, I mean never, have a distribution that is perfectly normally distributed. The idea is that if your distribution somewhat resembles the bell curve, calculate things like Cpk in the usual fashion. So, if your distribution is significantly different from the normal, you might tell the…[Read more]

  • Savage replied to the topic Amazed in the forum General 12 years, 5 months ago

    I imagine that people assume that since you enter your e-mail address to post a question or response that it is available or seen by others.

  • Look at a company called Dbar-innovations.

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