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  1. C

    Calculating Ppk and Cpk. Am I doing this right?

    Thank you for the very clear and precise answer! I think we have a few shortcomings at my end. I really appreciate your help, and I am trying my best to understand. As an example, for another set of data than the original in this thread, I have compared the output of out statistical software...
  2. C

    Calculating Ppk and Cpk. Am I doing this right?

    Hi again Back from holiday - I was thinking. Are there any way that tolerances should be part of these equations? The guy down at the department is not happy with me suggesting that they might also use the range chart as opposed to a combined X-bar and range chart. He tells me that I need to...
  3. C

    Calculating Ppk and Cpk. Am I doing this right?

    Hi again I was wondering - regarding the UCL for the range chart - what is the reasoning behind that level? If I understand it correctly, that is a calculated level, yes? or should it be specified? Thanks!
  4. C

    Calculating Ppk and Cpk. Am I doing this right?

    @Miner Thank you very much for this! I hope it is OK for me to ask some questions - I am trying to understand, and not just using automation. Which is where I believe we are at fault at my company. This is not my area, I just got hooked on trying to figure it out. My target value is 4.080...
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    Calculating Ppk and Cpk. Am I doing this right?

    Miner, Thanks for your reply - I will check out the other forums. Thanks for agreeing to check my calculations. I have edited the first post, there should now be 42 measurements. I also attached a picture - to visualize the groupings (samples of 2) and the range. I am looking very much forward...
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    Calculating Ppk and Cpk. Am I doing this right?

    Hi all. I am trying to make sure that I am doing this the right way. I hope you guys will look through my calculations. First, I have a list of 42 measurements. They are presented lower on the page. LSL = 4.070, USL = 4.090. Now, I want to calculate Ppk from the data. I take the mean and SD of...
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    Removing influences (operator, material differences) from samples

    Hi all I will try to explain to the best of my abilities. My coworker and I has been tasked with finding out how a turning machine in our production facility performs, but we have do this retrospectively - if possible, we will use data from very recent productions. The machine is running for...
  8. C

    R: is my t.test and reasoning correct?

    I did a f.test before the t.test: > var.test(C, f) Welch Two Sample t-test data: C and f t = 2.099, df = 7.2065, p-value = 0.07285 alternative hypothesis: true difference in means is not equal to 0 95 percent confidence interval: -0.1822245 3.2179388 sample estimates: mean of x mean...
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    R: is my t.test and reasoning correct?

    Hi all. My first post here :) I am doing my master's, and I have samples from two different places. I have been measuring aerobic bacterial counts, 7 from place C and 4 from place f. I want to ascertain if there is a difference :) C <- c(6.9, 8.2, 9.4, 9.2, 7.3, 6, 8.6) f <- c(5.4, 7.1...