• The short answer to your question is there aren’t any tests like that. In order to make a meaningful comparison of any kind you need context. Comparing one single number with another single number is a comparison devoid of context. The only thing you can say about any observed difference between two single numbers is a difference exists.

    The…[Read more]

  • Is there any way of getting this done? – Yes, start over because, based on your description of what you are doing, you are a very long way from being able to make any kind of decisions concerning employee performance.

    Let’s do a recap of your initial post.

    1. You said,”We convert the survey responses into continuous data (ex.: Liker scale 1 to…[Read more]

  • @michaelcyger great response….. though I’m way behind on the praise! 1 year, 2 months ago

  • If you can use excel faster…do that and then copy into their Minitab worksheet.

    1 year, 2 months ago

  • @rbutler brings up excellent points.

    See if you can quickly change your measurement system to a variable/continuous data system and confirm it’s performing with an MSA. You’ll solve your problem well and faster and learn more about the process if you are able. 1 year, 3 months ago

  • My guess would be your friend did something wrong in Minitab. If you don’t have subgroups then there is no within to use for calculations. Is there any chance the standard deviation it did compute was either just the sample standard deviation of all 60 points or the standard deviation of the mean of the 60 data points? 1 year, 3 months ago

  • A Google search will provide you with what you need.

    Here’s one I found for Cpk 1 year, 3 months ago

  • When you say you “have a lot of Attribute data for my analysis (Pass/Fail)” there isn’t much anyone can offer because that statement doesn’t tell anyone what you mean by “a lot.”

    However, if we make the following assumptions:
    1. You take grab samples of a given size from your production process and you inspect each item in the sample…[Read more]

  • Addendum – I played around with the data you posted and I must admit I don’t see how Minitab generated those estimates. The average of the non-missing data is -14.1 and the standard deviation of the non-missing data is 90.9 which means your 2 sigma limits would be (upper) = -14.1 +2*90.9 = 167.7 and the lower would be -195.9.

    If I substitute…[Read more]

  • A missing value is a missing value – what you have done is construct an entirely different set of data with a lot of average values in place of the original missing values. Under these circumstances you should expect to get something different because the two data sets are not equivalent.

    I don’t have Minitab but my guess is that Minitab is…[Read more]

  • As written, your post doesn’t provide enough information concerning your objective. My guess is that you are looking for tester agreement when running tests on split samples but maybe not. If you are looking for agreement then that is not the same thing as correlation and you will need more than a simple check of correlation to determine…[Read more]

  • It looks like excel is just computing the standard deviation of the sample and then giving you the plus/minus 2 standard deviations of the sample whereas Minitab looks like it is computing USL and LSL spec limits 1 year, 4 months ago

  • @Harshada99 The readers of iSixSigma are not here to do your work for you. Try using our search functionality. We have 20 years of content that should help you answer your questions. 1 year, 4 months ago

  • @Darth – things are going well here – how about you and yours? 1 year, 4 months ago

  • Given what you have posted, I think you are faced with one of two scenarios.

    (In order to provide some clarity with respect to what follows let’s pretend the treatment has as part of its application changes in temperature and pressure. Given this then there are at least two different versions of “no treatment”.)

    1. The situation for “no…[Read more]

  • @rbutler Robert, as usual, a concise simple to understand explanation LOL. I always learn so much from your posts…at least the parts that I understand. Hope all is well. 1 year, 4 months ago

  • Darth is correct. Here’s the relevant quote from a standard statistics text.

    Applied Regression Analysis 2nd Edition – Draper and Smith pages 22 and 23

    “[with regard to regression] Up to this point we have made no assumptions at all that involve probability distributions. A number of specified algebraic calculations have been made and tha…[Read more]

  • @shar6580 Double check the correctness of your assumptions. The only assumption for normality is in the residuals. There is no normality assumption for the raw data. Save your efforts of all those transformations. 1 year, 4 months ago

  • As for the second link the following commentary from their site

    “Consider the two regression models, and their residuals plots, shown here:

    The (lower) plots show the residuals for each model (the residuals are the errors between the regression lines and the actual data points). It can be seen that:

    1) The residuals for the ‘good’ reg…[Read more]

  • Well, the best I can tell you is what I said in my first post – most of what you quoted is wrong.

    Specifically – to the points made on the first site:

    “There are four assumptions associated with a linear regression model:”

    Linearity: The relationship between X and the mean of Y is linear. ”

    Not true – see the reference I gave in the…[Read more]

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