Additional questions to the ones below in my earlier e-mail. Is there a formula I can use for computing the b intercept under problem 2.2 or a R command I can use. I created an OLS function in 2.1 and am using that in 2.2, but my OLS function in 2.1 doesn't produce a b intercept, only a residual. If you give me the formula for b intercept, I'll code it in R.

And I thought that in the handouts there was instructions about how to name parts of a dataset (like naming columns, etc.). I couldn't find this in the notes and couldn't find online help in R on this using the '?' command. I haven't been able to load the PS1_Data yet, but can you tell me where to find out about how to name the parts of the data as I'll need to define this as X and Y for my OLS function.

Sorry for the *getting up to speed* questions. Thanks. Tom This is coding that I have #2.1 OLS<-function(x,y) { x<-cbind(matrix(1,nrow(x),1),x) # ADD COLUMN of 1s TO X coeff<-solve(t(x)%*%x)%*%(t(x)%*%y) #make coeff equal to X-prime times X times x-prime times y u<-y-(x%*%coeff) # Create the error term from the residuals of y-Beta times x sigmahatsq<-(t(u)%*%u)/(nrow(y)-(ncol(x))) #create sigma hat-squared = u-prime times u over n-k+1 # note since I had already added a column of 1s to x I used number of columns of x, no x+1 return(coeff,sigmahatsq,u) } #2.2 run OLS and compute intercept on PS1_Data.RData setwd(dir="C:/Documents and Settings/tsander/My Documents1/Mdrivebkp/E2001") load(PS1_Data.RData) data head(data) tail(data) summary(data) #name y as the y part of data #name x as the explanatory variables part of data OLS(x,y) # compute intercept NEED TO GET FORMULA *Thomas Sander* Executive Director Saguaro Seminar: Civic Engagement in America Harvard Kennedy School, Harvard University 79 JFK Street, Taubman 364, Cambridge, MA 02138 T - 617.496-2764 F - 617.495.1589 tom_sander at harvard.edu www.hks.harvard.edu/saguaro new - socialcapitalblog <http://socialcapital.wordpress.com/> *Please consider the environment before printing this e-mail* ----- Forwarded by Thomas Sander/FS/KSG on 02/10/2009 09:57 AM ----- *Thomas Sander/FS/KSG* 02/10/2009 09:19 AM To plam at fas.harvard.edu cc Subject Couple of other questions Patrick -- A couple of questions: 1) I can't seem to figure out how to use the Histogram function. I tried ?Hist and didn't really understand the documentation, perhaps because I don't have a clear sense of what par(mfrow=c(5,5)) is doing. Is there a better place to look to understand examples of how to specify what it is doing a histogram for 1.2.2 but I'm clearly missing something I have show<-par(mfrow=c(5,5)) for (i in 1:25) { hist(show[i,]) } 2) I can't seem to figure out how to load in the PS1_Data. I set the wd to be where I keep the data and then loaded the data setwd(dir="C:/Documents and Settings/tsander/My Documents1/MDrivebkp/E2001") load(PS1_Data) I also tried load(PS1_Data.RData) but in both cases, while it accepts the setwd command, it gives me an error on the load command: Error in load(PS1_Data.RData) : object "PS1_Data.RData" not found Any advice? 3) finally, is there a command to count whether there are odd items in a vector? I have kludgy code that sees whether the length of a vector divided by 2 and then truncated is not equal to the lenth of a vector divided by 2, but there must be a more elegant way to do this, and my code doesn't seem to be working. Many thanks. Best. Tom *Thomas Sander* Executive Director Saguaro Seminar: Civic Engagement in America Harvard Kennedy School, Harvard University 79 JFK Street, Taubman 364, Cambridge, MA 02138 T - 617.496-2764 F - 617.495.1589 tom_sander at harvard.edu www.hks.harvard.edu/saguaro new - socialcapitalblog <http://socialcapital.wordpress.com/> *Please consider the environment before printing this e-mail*