iSixSigma

P Value

Viewing 7 posts - 1 through 7 (of 7 total)
  • Author
    Posts
  • #45412

    Tahir Masood
    Member

    We reject null ypothesis when the p value is less than 0.05 ,but what happens when it is equal to 0.05.Do we still reject the null hypothesis or is it other wise.
    Help me and oblige. 

    0
    #148356

    clb1
    Participant

      You said “We reject null ypothesis when the p value is less than 0.05 ”  In this instance p = .05.  If p = .05 then p is not less than .05 therefore you cannot reject the null given that your rejection criteria was that you would reject if and only if p < .05.

    0
    #148358

    Waste
    Member

    Lol, is this a one-sided or two-sided hypothesis?

    0
    #148359

    Darth
    Participant

    The real answer is, “It depends”.  The .05 is just a guideline.  Since you could just have easily used p=.10 or .08 or any number, it is just a guideline for you to make a decision.  In fact, .05 is pretty restrictive and if your data is sloppy you might even use p=.15.  If you have a better understanding of what the p value really means you might be able to understand why judgement is sometimes called for and not just strict adherance to a guideline and whether the p value equals it or is less/greater than.

    0
    #148365

    mand
    Member

    You can set it at any value you want, depending who you are trying to fool … common practise by drug companies.
     

    0
    #148366

    Darth
    Participant

    LOW BLOW!!  Not sure that the FDA would approve a drug with a p value of .15.  They are usually lower than that….a good bit lower.

    0
    #148367

    EdG
    Participant

    Generally, one rejects the null hypothesis if the p-value is smaller than or equal to the significance level, often represented by the Greek letter á (alpha).  If the level is 0.05, then the results are only 5% likely to be as extraordinary as just seen, given that the null hypothesis is true.
    Based upon your own statement you are rejecting null hypothesis when the p value is less than 0.05 so your results are 4.99999% likely to be as extraordinary as just seen, given that the null hypothesis is true.

    0
Viewing 7 posts - 1 through 7 (of 7 total)

The forum ‘General’ is closed to new topics and replies.