TUESDAY, JULY 25, 2017
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MBBinWI

  • When doing the One-way ANOVA, the means are the means of the groups associated with the factors.

    @joelatminitab who’s your replacement again? can’t remember!

  • If you look at the equations for alpha and beta they are of the form

    alpha equation: (Ybarc – Xbar1)/(sigma/sqrt(n)) = -1.645 ( for alpha = .05)
    beta equation: (Ybarc – Xbar2)/(sigma/sqrt(n)) = ?

    Where Ybarc is the point between the two means (Xbar1 and Xbar2) that will be the cut point for accepting or rejecting the null hypothesis.

    If you…[Read more]

  • I like the simple concept of the 3 “pillars” of execution, strategy, and infrastructure.

  • consider looking at the range among the 3 operator xbar results for each chart–you should see it’s not looking good as a gauge.

  • no attachment seen

  • Arslan — How do you think the problem should be solved? What have you tried? Where are you running into a problem? You’re far more likely to receive helpful responses if you show that you’ve put forth a good-faith effort to solve your problem before asking for assistance. The iSixSigma audience can be exceptionally helpful, but they are not here…[Read more]

  • You are right – seeing the data does make a difference. Given what you have the approach I outlined in my last post won’t work. If we take your data set and check the X’s for independence they have enough to permit the inclusion of all of them in a multivariable model. If you run backward elimination on a model of the form…[Read more]

  • Since you only assign one X to a given failure the best bet would be to run a logistic regression with the response being pass/fail and the X’s coded as 0/1 (No/Yes) for occurrence. The coefficients of the output of a logistic regression are odds ratios and they express the odds of occurrence of a success for the occurrence of a given X.

    If…[Read more]

  • it’s a busy morning, are you sure you set up the machines as each operator and had each machine test each item 3X

  • Question: How many deliveries do you have in 26 days?
    Question: How do you know that a 26 day sample is at all representative?
    Question: Does the existence of any one of the X’s result in a failure or do you have some kind of overlapping where a failure might have one or more of the X’s?

    Based on what you have written I would not recommend…[Read more]

  • post the results of the gage R&R it might help.

  • Do you have a champion for doing this? I would suggest having a metric to track for your processes you’re wanting to standardize. Standardization won’t always be best if best practices aren’t implemented.

    Just a few thoughts.

  • Chapter 9 of Bothes’s book Measuring Process Capability covers all of the different ways one can calculate Cpk from attribute data. It’s too long to try to quote on a forum of this type but you should be able to get the book through inter-library loan. If you type in “calculating Cpk using attribute data” on Google you will get 100,000 or so…[Read more]

  • Chapter 9 of Bothes’s book Measuring Process Capability covers all of the different ways one can calculate Cpk from attribute data. It’s too long to try to quote on a forum of this type but you should be able to get the book through inter-library loan. If you type in “calculating Cpk using attribute data” on Google you will get 100,000 or so…[Read more]

  • @cseider Contrary to how some of my posts about the t-test sound I too am not adverse to using other tests to check for population differences. The fact is that the Wilcoxon-Mann-Whitney test can be used anywhere the t-test is used and it can handle crazy non-normal data and find a significant difference where a t-test with the same data would…[Read more]

  • @rbutler Nicely done. ;)

    We do know that traditionally t-tests are considered for normal distributions. I know I’ve read your comments and other research saying they are robust enough with non-normal data but IF one has to “pick” the test to get the probability wanted–it might not be a root cause being tested ;) I don’t mind advising folks…[Read more]

  • @cseider it probably comes from the same people who have provided us with other nifty alt-facts of statistics such as:

    1. You should try to have sample sizes of 30 because the central limit theorem states that samples of this size will be normally distributed.

    2. In order to use the t-test the data must be normal.
    2a. In order to use the t-test…[Read more]

  • @rbutler

    I’ve seen others make that statement about regressions needing normal data….where/when did that horrible impression creep into people’s minds?

    I have a theory…

  • Would you please be more specific? How far is “out”? – 1,2,or 3 standard deviations? Greater than 1.5 IQR? or is it some other measure?

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