Re: [R] multivariate problem

2012-01-08 Thread Clifford Long
Would some type of multivariate SPC be useful? Potentially useful options might include those based on SPC using PCA, or perhaps Hotelling's T2. Maybe you would find something useful in a package such as rrcov? http://cran.r-project.org/web/packages/rrcov/vignettes/rrcov.pdf R/S Cliff On

Re: [R] using plot with time series object - axes = FALSE option does not appear to work

2011-01-03 Thread Clifford Long
, Clifford Long gnolff...@gmail.com wrote: Dear R-help, I am attempting to plot data using standard R plot utilities.  The data was retrieved from FRED (St. Louis Federal Reserve) using the package quantmod.  My question is NOT about quantmod.  While I retrieve data using quantmod, I am

[R] using plot with time series object - axes = FALSE option does not appear to work

2011-01-02 Thread Clifford Long
Dear R-help, I am attempting to plot data using standard R plot utilities. The data was retrieved from FRED (St. Louis Federal Reserve) using the package quantmod. My question is NOT about quantmod. While I retrieve data using quantmod, I am not using its charting utility. I have been having

Re: [R] Homogeneity of regression slopes

2010-09-14 Thread Clifford Long
Hi Thomas, Thanks for the additional information. Just wondering, and hoping to learn ... would any lack of homogeneity of variance (which is what I believe you mean by different stddev estimates) be found when performing standard regression diagnostics, such as residual plots, Levene's test (or

Re: [R] Homogeneity of regression slopes

2010-09-13 Thread Clifford Long
If you'll allow me to throw in two cents ... Like Michael said, the dummy variable route is the way to go, but I believe that the coefficients on the dummy variables test for equal intercepts. For equality of slopes, do we need the interaction between the dummy variable and the explanatory

Re: [R] Simulating points from GLM corresponding to new x-values

2009-08-12 Thread Clifford Long
Would the predict routine (using 'newdata') do what you need? Cliff Long Hollister Incorporated On Wed, Aug 12, 2009 at 4:33 AM, Jacob Nabe-Nielsenjacobn...@me.com wrote: Dear List, Does anyone know how to simulate data from a GLM object correponding to values of the independent (x)

Re: [R] Simulating points from GLM corresponding to new x-values

2009-08-12 Thread Clifford Long
be applied to glms (with family=gaussian or binomial). Any suggestions for how to proceed? Jacob On 12 Aug 2009, at 13:11, Clifford Long wrote: Would the predict routine (using 'newdata') do what you need? Cliff Long Hollister Incorporated On Wed, Aug 12, 2009 at 4:33 AM, Jacob Nabe

[R] ROC curve using epicalc (after logistic regression) (re-sent)

2009-07-27 Thread Clifford Long
message -- From: Clifford Long gnolff...@gmail.com Date: Sun, Jul 26, 2009 at 8:46 PM Subject: Fwd: ROC curve using epicalc (after logistic regression) To: cvira...@medicine.psu.ac.th Dear Virasakdi Chongsuvivatwong, After sending the message below to the R-help mailing list, it occurred

[R] ROC curve using epicalc (after logistic regression)

2009-07-26 Thread Clifford Long
Dear R-help list, I'm attempting to use the ROC routine from the epicalc package after performing a logistic regression analysis. My code is included after the sessionInfo() result. The datafile (GasketMelt1.csv) is attached. I updated both R and the epicalc packages and tried again before

[R] Fwd: question about using _apply and/or aggregate functions

2009-06-22 Thread Clifford Long
Resending, as am not sure about the original To: address. Sorry for any redundancy. - Cliff -- Forwarded message -- From: Clifford Long gnolff...@gmail.com Date: Mon, Jun 22, 2009 at 11:04 AM Subject: question about using _apply and/or aggregate functions To: r-h...@lists.r

[R] question about using _apply and/or aggregate functions

2009-06-22 Thread Clifford Long
Hi R-list, I'll apologize in advance for (1) the wordiness of my note (not sure how to avoid it) and (2) any deficiencies on my part that lead to my difficulties. I have an application with several stages that is meant to simulate and explore different scenarios with respect to product sales (in

Re: [R] question about using _apply and/or aggregate functions

2009-06-22 Thread Clifford Long
the time outside of your day job for your earlier reply! Cliff On Mon, Jun 22, 2009 at 11:28 AM, David Winsemiusdwinsem...@comcast.net wrote: On Jun 22, 2009, at 12:04 PM, Clifford Long wrote: Hi R-list, I'll apologize in advance for (1) the wordiness of my note (not sure how to avoid

Re: [R] question about using _apply and/or aggregate functions

2009-06-22 Thread Clifford Long
:16 PM, Clifford Long wrote: Hi David, I appreciate the advice.  I had coerced 'list4' to as.list, but forgot to specify list=() in the call to aggregate.  I made the correction, and now get the following: slope.mult = simarray[,1] adj.slope.value = simarray[,2] adj.slope.level = simarray

Re: [R] p-values for ARIMA coefficients

2009-06-22 Thread Clifford Long
Hi Myriam, I'll take a stab at it, but can't offer elegance in the solution such as the more experienced R folks might deliver. I believe that the ARIMA function provides both point estimates and their standard errors for the coefficients. You can use these as you might a mean and standard