Comments on: Tues Feb 21 http://www.stat.cmu.edu/~kass/smnp/?p=92 Thu, 26 Apr 2012 14:07:02 +0000 hourly 1 http://wordpress.org/?v=3.0.4 By: Rich Truncellito http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-138 Rich Truncellito Thu, 23 Feb 2012 14:29:48 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-138 Does subtracting the mean of the x variable also work to reduce correlations of x with other transformations of x than x^2? Also, could you explain what AIC and BIC are? Does subtracting the mean of the x variable also work to reduce correlations of x with other transformations of x than x^2?

Also, could you explain what AIC and BIC are?

]]> By: Thomas Kraynak http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-137 Thomas Kraynak Thu, 23 Feb 2012 14:25:24 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-137 Can you go over why the one-way ANOVA splits up the variability into group and individual variability? Can you go over why the one-way ANOVA splits up the variability into group and individual variability?

]]> By: Yijuan Du http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-136 Yijuan Du Thu, 23 Feb 2012 12:51:48 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-136 In 12.4 Correlation and Regression Is there a preference of using correlation or regression under some conditions? In 12.4 Correlation and Regression
Is there a preference of using correlation or regression under some conditions?

]]> By: mpanico http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-135 mpanico Thu, 23 Feb 2012 06:38:12 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-135 In the finger-tapping example used for the two-way ANOVA, would it have been reasonable to subtract out the placebo rate as a "baseline" from each individual and compare the on-drug changes to a no-change case? In the finger-tapping example used for the two-way ANOVA, would it have been reasonable to subtract out the placebo rate as a “baseline” from each individual and compare the on-drug changes to a no-change case?

]]> By: Ben Dichter http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-134 Ben Dichter Thu, 23 Feb 2012 06:29:56 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-134 When doing linear regression over many variables, isn't there an increasing risk of overfitting? How do you know if you are overfitting and how do you choose parameters accordingly? When doing linear regression over many variables, isn’t there an increasing risk of overfitting? How do you know if you are overfitting and how do you choose parameters accordingly?

]]> By: Rex Tien http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-133 Rex Tien Thu, 23 Feb 2012 04:45:15 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-133 I guess my question is, is there a measure that might tell us when to claim the two variables are unrelated, or when to seek out a highly non-linear relationship? I guess my question is, is there a measure that might tell us when to claim the two variables are unrelated, or when to seek out a highly non-linear relationship?

]]> By: Sharlene Flesher http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-132 Sharlene Flesher Thu, 23 Feb 2012 04:43:06 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-132 Can you reiterate how the degrees of freedom for the error are determined? Can you reiterate how the degrees of freedom for the error are determined?

]]> By: Rex Tien http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-131 Rex Tien Thu, 23 Feb 2012 04:31:15 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-131 The R^2 measure can tell us if two things are linearly related. However, a low R^2 measure could mean the points are totally scattered or that they follow a highly non-linear relationship. Is there a measure of how "continuous" or "tight" the points are? (i.e. something that would be high when the points are arranged in a sine wave, and low when the points are scattered) Or do we have to just do it by eye? The R^2 measure can tell us if two things are linearly related. However, a low R^2 measure could mean the points are totally scattered or that they follow a highly non-linear relationship. Is there a measure of how “continuous” or “tight” the points are? (i.e. something that would be high when the points are arranged in a sine wave, and low when the points are scattered) Or do we have to just do it by eye?

]]> By: Rob Rasmussen http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-130 Rob Rasmussen Thu, 23 Feb 2012 02:44:33 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-130 I am confused by the purpose of anova. When there are more than two groups, it seems to be throwing information away. Why not just use multiple different t-tests - it seems like it would be a rare case where there would be so many groups that doing t-tests would be too cumbersome. I am confused by the purpose of anova. When there are more than two groups, it seems to be throwing information away. Why not just use multiple different t-tests – it seems like it would be a rare case where there would be so many groups that doing t-tests would be too cumbersome.

]]> By: Shubham Debnath http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-128 Shubham Debnath Wed, 22 Feb 2012 17:11:13 +0000 http://www.stat.cmu.edu/~kass/smnp/?p=92#comment-128 Trying to use ANOVA now...this chapter is a good resource and will be useful. Trying to use ANOVA now…this chapter is a good resource and will be useful.

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