Comments on: Thurs Mar 29 http://www.stat.cmu.edu/~kass/smnp/?p=112 Thu, 26 Apr 2012 14:07:02 +0000 hourly 1 http://wordpress.org/?v=3.0.4 By: Scott Kennedy http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-255 Scott Kennedy Thu, 29 Mar 2012 13:29:07 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-255 The details of the rank-sum test are still a little hazy to me. Can we go over it in class? The details of the rank-sum test are still a little hazy to me. Can we go over it in class?

]]> By: Rex Tien http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-254 Rex Tien Thu, 29 Mar 2012 13:20:53 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-254 I don't quite get the intuitive leap from ANOVA interactions to the multiplication of x1 and x2 in the linear regression case. Is x1*x2 just a special case? Can we look at other combinations of x1 and x2? Is there a form of rank-based ANOVA that preserves information about the absolute differences between consecutive ranks? Or is it really not that important? What assumptions, if any, are necessary for rank-based procedures? I don’t quite get the intuitive leap from ANOVA interactions to the multiplication of x1 and x2 in the linear regression case. Is x1*x2 just a special case? Can we look at other combinations of x1 and x2?

Is there a form of rank-based ANOVA that preserves information about the absolute differences between consecutive ranks? Or is it really not that important? What assumptions, if any, are necessary for rank-based procedures?

]]> By: Rob Rasmussen http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-253 Rob Rasmussen Thu, 29 Mar 2012 13:12:25 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-253 What are the main drawbacks to the rank-sum test? It seems to help minimize the effects of what appear as outliers but it seems like it could be hiding potentially important data. What are the main drawbacks to the rank-sum test? It seems to help minimize the effects of what appear as outliers but it seems like it could be hiding potentially important data.

]]> By: Amanda Markey http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-252 Amanda Markey Thu, 29 Mar 2012 12:51:47 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-252 Is there a difference in models between 2-way between subjects (where there is still only 1 subject per condition) and 2-way within subjects (where one subject experiences all conditions)? Is there a difference in models between 2-way between subjects (where there is still only 1 subject per condition) and 2-way within subjects (where one subject experiences all conditions)?

]]> By: Yijuan Du http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-251 Yijuan Du Thu, 29 Mar 2012 12:00:04 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-251 In 13.4, the usual F test on log trasformed data and rank based test have similar results. Do they usually show similar results? Should we consider transformation before using the rank test? For rank based procedure and permutation/ bootstrap, is there a preference choosing one over another under some conditions? In 13.4, the usual F test on log trasformed data and rank based test have similar results. Do they usually show similar results? Should we consider transformation before using the rank test?

For rank based procedure and permutation/ bootstrap, is there a preference choosing one over another under some conditions?

]]> By: Shubham Debnath http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-250 Shubham Debnath Thu, 29 Mar 2012 11:38:36 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-250 Can you provide some more detail on the Kruskal-Wallis Test? Can you provide some more detail on the Kruskal-Wallis Test?

]]> By: Matt Panico http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-249 Matt Panico Thu, 29 Mar 2012 09:22:15 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-249 You mention a couple options for matrices of indicator variables. Is one generally preferable to the other? You mention a couple options for matrices of indicator variables. Is one generally preferable to the other?

]]> By: David Zhou http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-248 David Zhou Thu, 29 Mar 2012 09:04:51 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-248 You write that the procedures of non-parametric ANOVA methods continue to make the assumptions of additivity and independence of errors. How do these assumptions limit what can be said about non-parametric ANOVA? You write that the procedures of non-parametric ANOVA methods continue to make the assumptions of additivity and independence of errors. How do these assumptions limit what can be said about non-parametric ANOVA?

]]> By: Jay Scott http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-247 Jay Scott Thu, 29 Mar 2012 04:04:45 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-247 sec 13.2.1: Is the notation X^T the trace of matrix X? How does that work when X is an nx1 vector of 1s? I am having difficulty with the notation on this page (421). sec 13.2.1: Is the notation X^T the trace of matrix X? How does that work when X is an nx1 vector of 1s? I am having difficulty with the notation on this page (421).

]]> By: Noah http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-246 Noah Thu, 29 Mar 2012 03:59:37 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=112#comment-246 After replacing distribution-free data by ranks to perform the rank-based ANOVA, can multiple comparison test be used (with the rankings) as they were for the parametric ANOVA. After replacing distribution-free data by ranks to perform the rank-based ANOVA, can multiple comparison test be used (with the rankings) as they were for the parametric ANOVA.

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