%0 Journal Article %T Effective Truncation of a Student¡¯s <i>t</i>-Distribution by Truncation of the Chi Distribution in a Chi-Normal Mixture %A Daniel T. Cassidy %J Open Journal of Statistics %P 519-525 %@ 2161-7198 %D 2012 %I Scientific Research Publishing %R 10.4236/ojs.2012.25067 %X A Student¡¯s t-distribution is obtained from a weighted average over the standard deviation of a normal distribution, ¦Ò, when 1/¦Ò is distributed as chi. Left truncation at q of the chi distribution in the mixing integral leads to an effectively truncated Student¡¯s t-distribution with tails that decay as exp (-q2t2). The effect of truncation of the chi distribution in a chi-normal mixture is investigated and expressions for the pdf, the variance, and the kurtosis of the t-like distribution that arises from the mixture of a left-truncated chi and a normal distribution are given for selected degrees of freedom <5. This work has value in pricing financial assets, in understanding the Student¡¯s t--distribution, in statistical inference, and in analysis of data. %K Asset Pricing %K Student¡¯s < %K i> %K t< %K /i> %K -Distribution %K Cauchy %K Truncation %K Moments %K Kurtosis %U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=25549