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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Dear Chris,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>First things first. TTR is highly dependent to text length so you have to be sure that the measurements have been taken from equal size text samples. Otherwise you should use a more robust index such as Yule’s K or Zipf’s Z (see the [1] for a detailed description of this problem). Now coming to your original question, TTR is a continuous variable and you could use the whole range of parametric statistics. This means that you can use a t-test if you want to check whether TTR is significant different across two classes (e.g. Gender distinction in essays), or ANOVA if your independent variable has many classes (e.g. Text Genre, Text Topic etc). You can also implement a linear regression model with dependent variable TTR and independent variables the ones that describe your research hypothesis. In all the above cases you need multiple TTR measurements because inferential statistics are based on the distribution parameters of the TTR. There is also the option to compare a single TTR value to a distribution of TTR values using one-sample location test (also called Z test) which actually can tell you how the specific TTR value lies away from the mean of the TTRs.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If the only thing you know are just 2 TTR values I don’t think you can compare them in any meaningful way.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Best<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>George Mikros<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>[1] Tweedie, Fiona J., & Baayen, Harald R. (1998). How variable may a constant be? Measures of lexical richness in perspective. Computers and the Humanities, 32(5), 323-352.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>____________________________<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>George K. Mikros<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Associate Professor of Computational and Quantitative Linguistics<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Department of Italian Language and Literature<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>School of Philosophy <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>National and Kapodistrian University of Athens <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Panepistimioupoli Zografou, GR-15784 <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Athens, Greece<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Tel: +30 210 7277491, +30 6976111742<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Email: <a href="mailto:gmikros@isll.uoa.gr">gmikros@isll.uoa.gr</a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Web: <a href="http://users.uoa.gr/~gmikros/">http://users.uoa.gr/~gmikros/</a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> <o:p></o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> corpora-bounces@uib.no [mailto:corpora-bounces@uib.no] <b>On Behalf Of </b>CRuehlemann@aol.com<br><b>Sent:</b> Sunday, November 20, 2011 7:21 PM<br><b>To:</b> CORPORA@uib.no<br><b>Subject:</b> [Corpora-List] Significance test for TTR<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>Hi all, <o:p></o:p></span></p><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>The type token ratio (TTR) is a measure of the lexical diversity of a text/text type. If one finds in two texts/text types two widely differing TTRs, one would like to assess the significance of this finding.<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>Which test is appropriate for differences between TTRs?<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>Best<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>Chris <o:p></o:p></span></p></div></div></div></body></html>