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Topic Help: What is a One-Sided Normal Distribution

Help: What is a One-Sided Normal Distribution

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This topic contains 3 replies, has 1 voice, and was last updated by Profile photo of BTDT BTDT 8 years, 10 months ago.

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  • #98109

    What is a One-Sided Normal Distribution?
    What is a One-Sided Specification?

    #98113

    Hmmm I have never heard of a one sided normal distribution.  There are one or two tail tests.. maybe that is what you mean?
    One sided specification means that you have a failure limit on the high or low side but not on both.

    #98210

    I guess it could be for a “barrier” type of feature, such as run-out on a shaft, flatness, etc.  Since 0 is the best it could be, there is only an “upper” tolerance.  This might answer both the distribution and the tolerance question.

    #98231

    A one sided normal distribution is better referred to as a “half-normal”
    distribution and consists of only the right or left h

    RickManCoffee:A one sided normal distribution is better referred to as a
    “half-normal” distribution and consists of only the right or left half of the
    bell shaped curve. It is observed and used when the parameter of interest has a
    natural upper or lower limit. Other cases are when only the absolute value of
    the measurement is used. I have seen it used while measuring:- Hole locations – deviations from center- Technical efficiency – where 100% is the maximum.- Wavelength correlation for matching spectra – where
    maximum correlation is 1.0- Deviations from standard operating temperature where
    previous data showed only positive deviations.- Contact resistance of an electrical bonding process –
    where the target is zero resistance. In order to calculate a process capability you can either:- Transform the data to a more normal (or at least
    symmetric) distribution and use a single specification limit using the normal
    distribution.- Assume a different distribution that has a natural limit
    on one or both sides. For example, assume a log-normal or binomial.- Calculate the process capability assuming and using only
    the half of the distribution that is applicable. I don’t know of any software
    that will allow this; you’ll have to do it by hand.  Neither assumption
    allows for the discussion or quantification of “centering”. Cheers, BTDT

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