Gov2001 March 2003

gov2001@lists.gking.harvard.edu

28 participants
102 discussions

[gov2001-l] formula for first difference via simulation

by olau＠fas.harvard.edu

Dear all, On p. 3 of the lecture notes, Gary gives 1/(1 + exp(-Xi %&% beta), but on p. 5 he gives 1/(1 + exp(X %*% beta). Is the exp() terms supposed to be negative or positive? Thanks, Olivia.

21 years, 1 month

[gov2001-l] getting sigma

by mjang＠fas.harvard.edu

I used glm and stored the result in a variable called "result". In order to extract sigma I'm doing the following: summary(result)$sigma but this is giving me null. am I calling it wrong or could I be doing calling something wrong when I run glm itself? thanks. ~mee-jung

21 years, 1 month

[gov2001-l] mvrnorm

by mjang＠fas.harvard.edu

what are the parameters that are sent to mvrnorm? I couldn't find it in R by doing "?mvrnorm" thanks! ~mee-jung

21 years, 1 month

[gov2001-l] Converting to pdf and keeping fonts nice

by reeves＠fas.harvard.edu

I know this has been asked before, but how do you keep smooth fonts what you convert a dvi file to pdf? Andrew -- -- Andrew Reeves reeves(a)fas.harvard.edu 617.493.3485 tel. 301.639.8369 cell. http://people.fas.harvard.edu/~reeves/

21 years, 1 month

[gov2001-l] p-value

by lipscy＠fas.harvard.edu

just as a clarification, when one implements: 1-pchisq(blah blah blah) What is the value we get? Is it the likelihood that the Null is correct? Or is it the likelihood that the Null is not correct?? Thanks, Phillip. ------------------------------------------------- Phillip Y. Lipscy Perkins Hall Room #129 35 Oxford Street Cambridge, MA 02138 (617)493-4893 DORM (617)851-8220 CELL lipscy(a)fas.harvard.edu http://www.people.fas.harvard.edu/~lipscy/ First Year Student, Ph.D. Program Harvard University, FAS, Department of Government -------------------------------------------------

21 years, 1 month

[gov2001-l] HW5 #2 (fwd)

by kimai＠fas.harvard.edu

You can use whatever command you like. But, if you are going to do the simulation for the first differences, you will end up calculating two sets of fitted values. Kosuke ---------- Forwarded message ---------- Date: Tue, 18 Mar 2003 16:52:35 -0500 (EST) To: Kosuke Imai <kimai(a)fas.harvard.edu> Subject: HW5 #2 Kosuke: To calculate the fitted values in number 2 on the homework, can we simply utilize the R command "fitted", or do you want us to write some function that effectively manually calculates all of the fitted values? Thanks,

21 years, 1 month

[gov2001-l] HWK 5 Q1A: Strange results

by dhopkins＠fas.harvard.edu

Dear Class, Several of us are getting consistently strange results on Q1, and I was curious if people had any thoughts. When we run the optim function, we get the following printout: > result2 <- optim(c(45,0.06,1.37,3.67,4.14), llik.1, method="BFGS", hessian=T, control=list(fnscale=-1)) > result2 $par [1] 45.00268155 -0.07857318 1.37203622 3.66731845 4.14000000 1. While some of these coefficients are pretty close, the final one is exactly what we fed into optim. (THe order is the same as in the assignment: intercept, ADAACA, JULYECQ2, INC, HOME4.) None match the LM results exactly. $value [1] -5528994 $counts function gradient 15 3 $convergence [1] 0 $message NULL $hessian [,1] [,2] [,3] [,4] [,5] [1,] -59.06099 3052.870 -44.88649 59.06099 0 [2,] 3052.86981 -157802.855 2320.18111 -3052.86981 0 [3,] -44.88649 2320.181 -34.11388 44.88649 0 [4,] 59.06099 -3052.870 44.88649 -59.06099 0 [5,] 0.00000 0.000 0.00000 0.00000 0 > 2. Notice too the row of all zeros in the Hessian. What does that mean? Might that explain why our results are strange? Best, Dan

21 years, 1 month

[gov2001-l] Q2: First Differences

by dhopkins＠fas.harvard.edu

Dear All, Quick query about question 2: is there an easy way to convince the glm function to do first differences, or should we be writing a function from scratch? Although the "xlevels" argument of "glm" looks like a promising possibility, I have yet to figure out how to use it properly, and R help is less than helpful... Many thanks! Best, Dan

21 years, 1 month

[gov2001-l] Q2 Fitted Values

by tburch＠fas.harvard.edu

This is a multi-part message in MIME format. ------=_NextPart_000_0074_01C2ECDC.FBF91300 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable For Q2 on the homework: To calculate fitted values, can we just substitute values for each x and = calculate the predicted MIL using the estimated betas or do we have to = do some sort of simulation? ------=_NextPart_000_0074_01C2ECDC.FBF91300 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=3DContent-Type content=3D"text/html; = charset=3Diso-8859-1"> <META content=3D"MSHTML 6.00.2719.2200" name=3DGENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=3D#ffffff> <DIV><FONT face=3DArial size=3D2>For Q2 on the homework:</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>To calculate fitted values, can we just = substitute=20 values for each x and calculate the predicted MIL using the estimated = betas or=20 do we have to do some sort of simulation?</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV></BODY></HTML> ------=_NextPart_000_0074_01C2ECDC.FBF91300--

21 years, 1 month

[gov2001-l] IMPORTANT: replication assignment

by kimai＠fas.harvard.edu

Hi everyone, A few things about the replication assignment: 1. First and most important, please turn in your assignment on time. Since the next assignment is going to be the replication of someone else's replication results, your late homework would cause a trouble for another student in the class. 2. You can use any statistical package you want. If it's easier, you can use SPSS, STATA, or whatever. The only reason we recommend that you use R is that it's a nice software that allows you to do more than SPSS or STATA. But, this assignment as well as all the other assignments will be evaluated solely based on its quality not on what program you used. 3. In your Hw#5, indicate the title of your replication article and your coauthor. 4. On March 31, "each" of you should turn in the following: (a) a floppy disk containing the data, the program, and the description of your replication procedure and results. (b) two hard copies of the description of your replication procedure and results. (c) a hard copy of the replication article. Good luck! Kosuke

21 years, 1 month

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Gov2001 March 2003