Re: [R] comparing two regression models with different dependent variable

2010-06-10 Thread Joris Meys
On Thu, Jun 10, 2010 at 2:04 PM, Gabor Grothendieck wrote: > On Thu, Jun 10, 2010 at 5:33 AM, Joris Meys wrote: >> This is only valid in case your X matrix is exactly the same, thus > > The poster did not give a full explanation so the best that can be > done without getting into an extended ques

Re: [R] comparing two regression models with different dependent variable

2010-06-10 Thread Gabor Grothendieck
On Thu, Jun 10, 2010 at 5:33 AM, Joris Meys wrote: > This is only valid in case your X matrix is exactly the same, thus The poster did not give a full explanation so the best that can be done without getting into an extended question and answer is to make some assumptions, show the result and hop

Re: [R] comparing two regression models with different dependent variable

2010-06-10 Thread Or Duek
Thank you very much for your answers. The setup is not as you described - all participants have 4 stimuli - 2 for punishment and 2 for reward. all participants see them in mixed blocks. I try to measure the correlation between some personality traits (measured with personality questionnaires) and t

Re: [R] comparing two regression models with different dependent variable

2010-06-10 Thread Joris Meys
As I explained, you cannot just test two models with different dependent variables. You can model the difference you calculated, if you think you can give a sensible interpretation to it. But be aware of the fact that your model will tell you something about the relation between your predictors and

Re: [R] comparing two regression models with different dependent variable

2010-06-10 Thread Or Duek
I'll try to add some more information regarding my experiment - maybe that would help clear things out. Instead of actually measuring the learning curve (i.e. number of correct responses per block) I created a variable that substract the number of correct answers from the last block with that of th

Re: [R] comparing two regression models with different dependent variable

2010-06-10 Thread Joris Meys
This is only valid in case your X matrix is exactly the same, thus when you have an experiment with multiple response variables (i.e. paired response data). When the data for both models come from a different experiment, it ends here. You also assume that y1 and y2 are measured in the same scale,

Re: [R] comparing two regression models with different dependent variable

2010-06-10 Thread Gabor Grothendieck
We need to define what it means for these models to be the same or different. With the usual lm assumptions suppose for i=1, 2 (the two models) that: y1 = a1 + X b1 + error1 y2 = a2 + X b2 + error2 which implies the following which also satisfies the usual lm assumptions: y1-y2 = (a1-a2) + X(b1

Re: [R] comparing two regression models with different dependent variable

2010-06-09 Thread Or Duek
Ok. Thank you very much for setting me straight :) On Wed, Jun 9, 2010 at 7:22 PM, Joris Meys wrote: > On Wed, Jun 9, 2010 at 5:19 PM, Or Duek wrote: > > Hi, > > I would like to compare to regression models - each model has a different > > dependent variable. > > The first model uses a number

Re: [R] comparing two regression models with different dependent variable

2010-06-09 Thread Joris Meys
On Wed, Jun 9, 2010 at 5:19 PM, Or Duek wrote: > Hi, > I would like to compare to regression models - each model has a different > dependent variable. > The first model uses a number that represents the learning curve for reward. > The second model uses a number that represents the learning curve

[R] comparing two regression models with different dependent variable

2010-06-09 Thread Or Duek
Hi, I would like to compare to regression models - each model has a different dependent variable. The first model uses a number that represents the learning curve for reward. The second model uses a number that represents the learning curve from punishment stimuli. The first model is significant an