Statistical tests are not one-tailed or two-tailed. They are simply the statistical test. With a t-test, you get positive and negative values. The issue of one-/two-tailed tests effects the interpretation and not the t-statistic itself.<div>
<br></div><div>In SPM, the inferences/p-values are based on only one-tail.</div><div>In other programs, the inferences/p-values are based on two-tails.</div><div><br clear="all">Best Regards, Donald McLaren<br>=================<br>
D.G. McLaren, Ph.D.<br>Postdoctoral Research Fellow, GRECC, Bedford VA<br>Research Fellow, Department of Neurology, Massachusetts General Hospital and <br>Harvard Medical School<br>Website: <a href="http://www.martinos.org/~mclaren" target="_blank">http://www.martinos.org/~mclaren</a><br>
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<br><br><div class="gmail_quote">On Mon, May 7, 2012 at 10:57 AM, lorenzo pasquini <span dir="ltr">&lt;<a href="mailto:[log in to unmask]" target="_blank"><a href="/cgi-bin/wa-jisc.exe?LOGON=A3%3Dind1205%26L%3DSPM%26E%3Dquoted-printable%26P%3D1484974%26B%3D--f46d044303f4eb029f04bf738ecd%26T%3Dtext%252Fhtml%3B%2520charset%3DISO-8859-1%26pending%3D" target="_parent" >[log in to unmask]</a></a>&gt;</span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div><div style="font-size:12pt;font-family:times new roman,new york,times,serif"><div>Dear SPM users,</div><div><br></div><div>I estimated an ANOVA model and I am doing several post hoc ttest now. I believe the ttest are two tailed, but I was not aible to find any additional information in manuals or publications. Can somebody confirm this intuition?:)</div>
<div>Thank you very much in advance and kind regards,</div><div><br></div><div>Lorenzo Pasquini</div></div></div></blockquote></div><br></div>