Re: [R] fitting a logistic regression with mixed type of variabl

2009-11-16 Thread Ted Harding
On 16-Nov-09 19:22:10, Jack Luo wrote: > Hi, > I am trying to fit a logistic regression using glm, but my > explanatory variables are of mixed type: some are numeric, > some are ordinal, some are categorical, say > > If x1 is numeric, x2 is ordinal, x3 is categorical, is the > following formula OK

Re: [R] fitting a logistic regression with mixed type of variables

2009-11-16 Thread David Winsemius
On Nov 16, 2009, at 2:53 PM, Jack Luo wrote: > David, > > Thanks for your reply. Since I am kinda new to this forum, could you > please advise me on where to read those questions in R-help? http://search.r-project.org/nmz.html http://search.r-project.org/cgi-bin/namazu.cgi?query=%22ordered+fa

Re: [R] fitting a logistic regression with mixed type of variables

2009-11-16 Thread Jack Luo
David, Thanks for your reply. Since I am kinda new to this forum, could you please advise me on where to read those questions in R-help? In addition, I did not pay much attention to the na.action, probably I should use na.action = na.omit instead of na.pass. -Jack On Mon, Nov 16, 2009 at 2:32 PM

Re: [R] fitting a logistic regression with mixed type of variables

2009-11-16 Thread David Winsemius
On Nov 16, 2009, at 2:22 PM, Jack Luo wrote: Hi, I am trying to fit a logistic regression using glm, but my explanatory variables are of mixed type: some are numeric, some are ordinal, some are categorical, say If x1 is numeric, x2 is ordinal, x3 is categorical, is the following formula

[R] fitting a logistic regression with mixed type of variables

2009-11-16 Thread Jack Luo
Hi, I am trying to fit a logistic regression using glm, but my explanatory variables are of mixed type: some are numeric, some are ordinal, some are categorical, say If x1 is numeric, x2 is ordinal, x3 is categorical, is the following formula OK? *model <- glm(y~x1+x2+x3, family=binomial(link="l

Re: [R] Fitting a logistic regression

2009-08-20 Thread Dani Valverde
Thank you very much, Jun. This is what I was looking for. Best! Dani On Wed, 2009-08-19 at 09:52 -0500, Jun Shen wrote: > I would suggest a model with a baseline level, something like > > nls(AMP~E0+(Emax-E0)*Time**gamma/(EC50**gamma+Time**gamma),data=your > data, > start=list(EC50=50,gamma=2,E

Re: [R] Fitting a logistic regression

2009-08-19 Thread Jun Shen
I would suggest a model with a baseline level, something like nls(AMP~E0+(Emax-E0)*Time**gamma/(EC50**gamma+Time**gamma),data=your data, start=list(EC50=50,gamma=2,E0=0.2,Emax=1.2))->mod.test AIC(mod.test) does improve. Hope this helps. Jun On Wed, Aug 19, 2009 at 5:04 AM, Dani Valverde wrote:

Re: [R] Fitting a logistic regression

2009-08-19 Thread 1Rnwb
with my limited understanding, I am not surprised to see this data fitting nicely at the end just by eyeballing at it. the reaction at the early time point is not completed as the time passes which is close to 20 units the reaction generates more metabolite to be measured reliably your t=0 and t=1

[R] Fitting a logistic regression

2009-08-19 Thread Dani Valverde
Hello, I have this data: Time AMP 0 0.200 10 0.1958350 20 0.2914560 40 0.6763628 60 0.8494534 90 0.9874526 120 1.0477692 where AMP is the concentration of this metabolite with time. If you plot the data, you can see that it could be fitted using a logistic regres