The shape of the NCT depends on the noncentrality parameter d. If d = 0, the NCT = STudent's t, and so it is symmetric about zero. If d > 0, it is right skewed; if d < 0, it is left skewed.
K. Krishnamoorthy ----- Original Message ----- From: "Paul R Swank" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Wednesday, November 20, 2002 10:48 AM Subject: Re: Two questions > As the websites posted below gave me some problems One couldn't be found and > the other froze in the middle), would someone please explain what has > happeded to the non-central t distribution since I last checked. If the > assumptions for t are met, that is, the observations are NID with equal > variances, why would the non-central t be asymmetric. > > Paul R. Swank, Ph.D. > Professor, Developmental Pediatrics > Medical School > UT Health Science Center at Houston > > > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On > Behalf Of David Wnsemius > Sent: Tuesday, November 19, 2002 11:31 PM > To: [EMAIL PROTECTED] > Subject: Re: Two questions > > > (I generally bottom post in newsgroups. See below. DW) > [EMAIL PROTECTED] (Paul R Swank) wrote in > 003601c28fd5$af678bc0$520e6a81@PEDUCT225:">news:003601c28fd5$af678bc0$520e6a81@PEDUCT225: > > > The non-central t is symmetric. > > > > Paul R. Swank, Ph.D. > > Professor, Developmental Pediatrics > > Medical School > > UT Health Science Center at Houston > > > > > I suggest you re-examine your belief: > http://www.itl.nist.gov/div898/software/dataplot.html/distribu.htm > and > http://www.itl.nist.gov/div898/software/dataplot.html/refman2/auxillar/nctp > df.pdf > > David Winsemius, MD, MPH > > . > . > ================================================================= > Instructions for joining and leaving this list, remarks about the > problem of INAPPROPRIATE MESSAGES, and archives are available at: > . http://jse.stat.ncsu.edu/ . > ================================================================= > > > . > . > ================================================================= > Instructions for joining and leaving this list, remarks about the > problem of INAPPROPRIATE MESSAGES, and archives are available at: > . http://jse.stat.ncsu.edu/ . > ================================================================= > > . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
