Displaying 20 results from an estimated 542 matches for "baltimore".
2006 Dec 09
7
Simulation with R
An apparatus exists whereby a collection of balls is displaced to the
top of a stack by suction. A top level (Level 1) each ball is shifted
1 unit to the left or 1 unit to the right at random with equal
probability. The ball then drops down to level 2. At Level 2, each
ball is again shifted 1 unit to the left or 1 unit to the right at
random. The process continues for 15 levels and the balls are
2007 Jan 18
3
selecting rows for inclusion in lm
...ength(data[,"Meno"]=="PRE","Meno"]))
[1] 22
I would appreciate any help in modifying the data= parameter of the lm
so that I include only those subjects for which Meno=PRE.
R 2.3.1
Windows XP
Thanks,
John
John Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
Baltimore VA Medical Center GRECC,
University of Maryland School of Medicine Claude D. Pepper OAIC,
University of Maryland Clinical Nutrition Research Unit, and
Baltimore VA Center Stroke of Excellence
University of Maryland School of Medicine
Division of Gerontology
Baltimore VA Medical Center
10 North Gre...
2007 Oct 01
4
data structure with coefficients, and call from lm()
...""),summary(myreg)$coefficients)
Neither the statement above, nor any one of twenty variations I have tried work. I would appreciate any advice.
Thanks,
John
John Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing)
Confidentiality Statement:
This email message, including any attachments, is for the so...{{dropped}}
2006 Nov 21
2
sample size for linear regression
...Given a linear regression:
y=f(x,z)
i.e. fit1<-lm(y~x+z)
is there a function which can be passed coef(z), SE(z), and other
parameters to determine a sample size based on z, SEz and other
information from the regression?
Thanks,
John
John Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
Baltimore VA Medical Center GRECC,
University of Maryland School of Medicine Claude D. Pepper OAIC,
University of Maryland Clinical Nutrition Research Unit, and
Baltimore VA Center Stroke of Excellence
University of Maryland School of Medicine
Division of Gerontology
Baltimore VA Medical Center
10 North Gre...
2005 Jul 28
4
CSV file and date. Dates are read as factors!
...ad as factors.
Because of this, I can not compute follow-up time, i.e.
Followup<-postDate-preDate. I would appreciate any suggestion that would
help me read the dates as dates and thus allow me to calculate follow-up
time.
Thanks
John
John Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
Baltimore VA Medical Center GRECC and
University of Maryland School of Medicine Claude Pepper OAIC
University of Maryland School of Medicine
Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
410-605-7119
- NOTE NEW EMAIL ADDRESS:
jsorkin a...
2005 Jul 15
3
Dividing a vector into ntiles
...n
be used to divide a vector into thirds such as 0-33 centile, 34-66
centile, 67-100 centile. If for example I had a vector:
1,2,3,4,5,6,7,8,9
and wanted to divide the vector into thirds
I would have cut-points of 3, and 6.
Thanks,
John
John Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
Baltimore VA Medical Center GRECC and
University of Maryland School of Medicine Claude Pepper OAIC
University of Maryland School of Medicine
Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
410-605-7119
- NOTE NEW EMAIL ADDRESS:
jsorkin...
2007 Feb 07
1
Problem with subsets and xyplot
Hello
I have a dataframe that looks like this
MSA CITY HIVEST YEAR YR CAT
1 0200 Albuquerque 0.50 1996 1996 5
2 0520 Atlanta 13.00 1997 1997 5
3 0720 Baltimore 29.10 1994 1994 1
4 0720 Baltimore 13.00 1995 1995 5
5 0720 Baltimore 3.68 1996 1996 3
6 0720 Baltimore 9.00 1997 1997 5
7 0720 Baltimore 11.00 1998 1998 5
8 0875 Berg...
2007 Mar 06
5
Recalling and printing multiple graphs. Is there something in the HISTORY menu that will help?
...not been able to find instructions for using
the HISTORY menu. Please take pity on my when you let me know that some
easy search or command could get me the information I needed. I have
looked, but clearly in the wrong places.
John
John Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
Baltimore VA Medical Center GRECC,
University of Maryland School of Medicine Claude D. Pepper OAIC,
University of Maryland Clinical Nutrition Research Unit, and
Baltimore VA Center Stroke of Excellence
University of Maryland School of Medicine
Division of Gerontology
Baltimore VA Medical Center
10 North Gre...
2007 Mar 26
4
Problem dropping rows based on values in a column
...19 15589 15982 15825 15834 15491 15822
[35] 15803 15795 10202 15680 15587 15552 15588 15375 15492 15568 15196 10217 15396 15477 15446 15374 14092
[52] 14033 15141 14953 15473 10424 13445 14854 10481 14793 14744 14772
>
Thanks,
John
John Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
Baltimore VA Medical Center GRECC,
University of Maryland School of Medicine Claude D. Pepper OAIC,
University of Maryland Clinical Nutrition Research Unit, and
Baltimore VA Center Stroke of Excellence
University of Maryland School of Medicine
Division of Gerontology
Baltimore VA Medical Center
10 North Gre...
2011 Jan 04
5
Page eject and clearing the console
...e?
(2) I know that control L will clear the console. Is there an equivalent function or other means that can be used in R code to clear the console?
Thanks,
John
John David Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing)
Confidentiality Statement:
This email message, including any attachments, is for th...{{dropped:6}}
2008 Oct 16
1
apply, t-test and p-values
...from the tests, but can't seem to get it to work. I have tried several methods to get the values including:
boo<-apply(sample1,1,t.test$t.test,sample2)
boo<-apply(sample1,1,t.test,sample2)$t.test
any suggestions?
Thanks
John
John Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
Baltimore VA Medical Center GRECC,
University of Maryland School of Medicine Claude D. Pepper OAIC,
University of Maryland Clinical Nutrition Research Unit, and
Baltimore VA Center Stroke of Excellence
University of Maryland School of Medicine
Division of Gerontology
Baltimore VA Medical Center
10 North Gre...
2006 Oct 14
2
regression analyses using a vector of means and a variance-covariance matrix
...indows XP
How can I perform a regression analyses using a vector of means, a
variance-covariance matrix? I looked at the help screen for lm and did
not see any option for using the afore mentioned structures as input to
lm.
Thanks,
John
John Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
Baltimore VA Medical Center GRECC,
University of Maryland School of Medicine Claude D. Pepper OAIC,
University of Maryland Clinical Nutrition Research Unit, and
Baltimore VA Center Stroke of Excellence
University of Maryland School of Medicine
Division of Gerontology
Baltimore VA Medical Center
10 North Gre...
2003 Sep 21
3
Samba PDC not creating roaming profiles
...ase inform us of its receipt by you. You are hereby notified that you must not disclose, copy, distribute or take any action in reliance of the contents of this information, which must be immediately deleted.
This e-mail was checked by the e-Sweeper Service.
For more information visit our website, Baltimore Technologies e-Sweeper :
http:// www.mimesweeper.baltimore.com/products/esweeper/
------------------------------------------------------------------------------------------
2006 Jul 03
6
macro facility in R
...iables with parameters passed to the macro, i.e. I need
someting akin to the macro facility in SAS. Is there a macro facility
that I can use with R? I have tried help.search("macro") and did not
have any success.
Thanks,
John
John Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
Baltimore VA Medical Center GRECC,
University of Maryland School of Medicine Claude D. Pepper OAIC,
University of Maryland Clinical Nutrition Research Unit, and
Baltimore VA Center Stroke of Excellence
University of Maryland School of Medicine
Division of Gerontology
Baltimore VA Medical Center
10 North Gre...
2006 May 12
4
Title of page with multiple plots
...yone have any suggestions?
R 2.1.1
windows xp
oldpar<-par(mfcol =c(1,4),ask=TRUE)
plot(p,varp)
plot(p,SEp)
plot(p,CVp)
plot(p,ppval)
title(paste("P and 95%CI for a sample size of",n,"subjects."))
Thanks,
John
John Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
Baltimore VA Medical Center GRECC and
University of Maryland School of Medicine Claude Pepper OAIC
University of Maryland School of Medicine
Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
410-605-7119
jsorkin at grecc.umaryland.edu
2006 Jul 10
1
How can I obtain the values of BIAS and STD. ERROR from a bootstrap.
...IGINAL and BIAS. I can get the
value of ORIGINAL:
> result2$t0
[1] 1.876602
But I can't find a way to get the values of BIAS or STD. ERROR. Can
someone suggest how I can obtain the values for these two statistics?
Thanks,
John
John Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
Baltimore VA Medical Center GRECC,
University of Maryland School of Medicine Claude D. Pepper OAIC,
University of Maryland Clinical Nutrition Research Unit, and
Baltimore VA Center Stroke of Excellence
University of Maryland School of Medicine
Division of Gerontology
Baltimore VA Medical Center
10 North Gre...
2007 Aug 02
1
Multivariable correlation
...ables taken together, i.e. for the matrix
X=x1 x2 x3
x4 x5 x6
x7 x8 x9
I don't want the pair-wise correlations corr(x1,x2), corr(x1,x3), corr(x1,x4) . . . etc., but rather
corr(x1,x2,x3,x4,x5,x6,x7,x8,x9).
Thanks,
John
John Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
Baltimore VA Medical Center GRECC,
University of Maryland School of Medicine Claude D. Pepper OAIC,
University of Maryland Clinical Nutrition Research Unit, and
Baltimore VA Center Stroke of Excellence
University of Maryland School of Medicine
Division of Gerontology
Baltimore VA Medical Center
10 North Gre...
2013 Feb 05
3
Non linear programming: choose R that minimizes corr(y, x^R)
...nimizes the correlation of y and x^R, i.e.
find R such that corr(y,x^R) is minimized. Any suggestions for packages I might look at would be helpful.
Thanks,
John
John David Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing)
Confidentiality Statement:
This email message, including any attachments, is for the sole use of the intended recipient(s) and...
2006 Nov 05
2
solution to a regression with multiple independent variable
...applies the matrix solution b=
(x'x)-1*x'y to the elements of the variance-covariance matrix, i.e. how
one gets the required values from the variance-covariance matrix.
Any help, or suggestions would be appreciated.
Thanks,
John
John Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
Baltimore VA Medical Center GRECC,
University of Maryland School of Medicine Claude D. Pepper OAIC,
University of Maryland Clinical Nutrition Research Unit, and
Baltimore VA Center Stroke of Excellence
University of Maryland School of Medicine
Division of Gerontology
Baltimore VA Medical Center
10 North Gre...
2007 Nov 21
3
Packages - a great resource, but hard to find the right one.
...that will allow a user to easily search for a given function or technique in all contributed packages?
Thanks,
John
P.S. Many thanks to the writers and maintainers of R packages and the many people who contribute to the R list server.
John Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
Baltimore VA Medical Center GRECC,
University of Maryland School of Medicine Claude D. Pepper OAIC,
University of Maryland Clinical Nutrition Research Unit, and
Baltimore VA Center Stroke of Excellence
University of Maryland School of Medicine
Division of Gerontology
Baltimore VA Medical Center
10 North Gre...