iSixSigma

normality

Viewing 8 posts - 1 through 8 (of 8 total)
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  • #47812

    Katrina
    Participant

    hey, what is the reasoning for the a value >0.05 to signify normality?! Why has this value been chosen as the cut off point?!
    thanks
    kat

    0
    #159861

    Aguilar
    Member

    http://www.sportsci.org/resource/stats/pvalues.html
    Just take a look at it,Hope it answers your query.
    Cheers

    0
    #159865

    Katrina
    Participant

    hey, thanks for your reply, hopefully will understand it once ive had a proper read
    cheers kat

    0
    #159873

    Katrina
    Participant

    hey, Ive read that article and im still not clear as to why a >0.05 value would signify that the data is normal?! why this value?!
    thanks
    kat

    0
    #159880

    Jim Shelor
    Participant

    Katrina,
    The value 0.05 comes from the confidence level you want for your answer.  If you want a confidence level of 95%, then if P<0.05, you reject the null hypothesis because the p is significant.
    In this case, the null hypothesis is the distribution is normal.  Therefore, a p<0.05 says to reject the null.  Accordingly, the distribution is not normal.
    If for this case, null hypothesis = distribution normal, your p>0.05, there is insufficient evidence to show the null is not true at the 95% confidence level and you fail to reject the null hypothesis.  Your distribution is normal.
    You can use a 90% confidence level, in which case the significant p level is 0.1; or a 99% confidence level in which case your significant p level is 0.01 (1-confidence).
    I hope this helps.
    Respects,
    Jim Shelor

    0
    #159885

    BTDT
    Participant

    Kat:The number is based on this statement from R.A. Fisher (1890-1962) on whether something that occurs is due to random chance or otherwise. It was pretty arbitrary, but everyone has come to agree to the 1 in 20 rule.“… either there is something in the treatment, or a coincidence has occurred such as does not occur in 1 in 20 trials” (Journal of the Ministry of Agriculture of Great Britain, 1926)Cheers, BTDT

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    #159905

    Katrina
    Participant

    thanks for your help guys, think i get it now, was over complicating things lol!
    cheers
    kat

    0
    #159907

    Tierradentro
    Participant

    I used to wonder about this too…. thanks for the question and the answer
    John
    Business Consultant
    http://www.pralayass.com

    0
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