Re: [R] Different result of multiple regression in R and SPSS
On Jul 19, 2011, at 7:19 PM, J. wrote: @Dimitri: I tried to enter it as numeric and still got the same outcome. I still wonder if there is any way to get the same result from both programs. @David, Bert: Yes, I found that the gender coefficient is R is exactly twice that of the one from SPSS. Need to study on parametrization. Yes. I tested my own advice and did a google search with "different parametrization of dummy variables spss and r". 1) http://support.spss.com/productsext/spss/documentation/statistics/articles/catreg3.htm 2) http://www.thejuliagroup.com/blog/?p=1531 3) I'm not sure it should be in a publicly accessible site, but Google links to a pdf of the full text of "Data Analysis and Graphics Using R – an Example-Based Approach: Third Edition" by Maindonald % Braun http://lib.dnu.dp.ua:8001/l/%D0%9A%D0%BE%D0%BF%D1%8C%D1%8E%D1%82%D0%B5%D1%80%D1%8B%D0%98%D1%81%D0%B5%D1%82%D0%B8/%D0%9F%D0%BE%D0%BF%D1%83%D0%BB%D1%8F%D1%80%D0%BD%D1%8B%D0%B5%20%D0%BF%D1%80%D0%BE%D0%B3%D1%80%D0%B0%D0%BC%D0%BC%D1%8B/S-PLUS%20R/Data%20Analysis%20and%20Graphics%20Using%20R%203rd%20Edition.pdf And chapter 7 would be where to look. Bottom line. You should only be looking at coefficient values when you know the coding of your factors. You cannot interpret the coefficients of an SPSS run as differences between males and females, because they are based on a -1 vs. 1 coding, what in R are called sum.contrasts. R uses a default of treatment contrasts (0 versus 1) but will offer sum.contrasts if asked nicely. (And you should never interpret "main effects" coefficients when you are using interactions in models. Always use predictions in that instance.) Thanks, Jay -- View this message in context: http://r.789695.n4.nabble.com/Different-result-of-multiple-regression-in-R-and-SPSS-tp3679423p3679590.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. David Winsemius, MD West Hartford, CT __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Different result of multiple regression in R and SPSS
On Tue, Jul 19, 2011 at 4:19 PM, J. wrote: > @Dimitri: I tried to enter it as numeric and still got the same outcome. I > still wonder if there is any way to get the same result from both programs. There is. ?C ?contrasts But of course you must do your homework to understand how to use these. (See the quote in my signature). -- Bert > @David, Bert: Yes, I found that the gender coefficient is R is exactly twice > that of the one from SPSS. Need to study on parametrization. > Thanks, > > Jay > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > -- "Men by nature long to get on to the ultimate truths, and will often be impatient with elementary studies or fight shy of them. If it were possible to reach the ultimate truths without the elementary studies usually prefixed to them, these would not be preparatory studies but superfluous diversions." -- Maimonides (1135-1204) Bert Gunter Genentech Nonclinical Biostatistics 467-7374 http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Different result of multiple regression in R and SPSS
At 19.07.2011 18:50 -0700, Spencer Graves wrote: On 7/19/2011 4:04 PM, Bert Gunter wrote: On Tue, Jul 19, 2011 at 3:45 PM, David Winsemius wrote: On Jul 19, 2011, at 6:29 PM, J. wrote: Thanks for the answer. # However, I am still curious about which result I should use? The result from R or the one from SPSS? It is becoming apparent that you do not know how to use the results from either system. The progress of science would be safer if you get some advice from a person that knows what they are doing. ## I nominate this for an R fortune. -- Bert None of us ever know what we're doing at some level. We often think we do, and sometimes we get results more in spite of what we've done than because of it. That of course increases our confidence and encourages us to repeat mistakes in contexts where we might not be so lucky. Spencer Wise! Heinz Why the results from two programs are different? Different parametrizations. If I had to guess I would bet that the gender coefficient is R is exactly twice that of the one from SPSS. They are probably both correct in the context of their respective codings. -- David Winsemius, MD West Hartford, CT __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. -- Spencer Graves, PE, PhD President and Chief Technology Officer Structure Inspection and Monitoring, Inc. 751 Emerson Ct. San José, CA 95126 ph: 408-655-4567 web: www.structuremonitoring.com __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Different result of multiple regression in R and SPSS
I finally got the same result by converting "gender" variable as numeric, and standardize it. I guess SPSS automatically doing the same thing when doing analysis. But, it still is not clear to me how I can interpret "standardized categorical (dummy coded)" variable. I'd rather stick to use R. Thanks for all the comments and advice. Jay -- View this message in context: http://r.789695.n4.nabble.com/Different-result-of-multiple-regression-in-R-and-SPSS-tp3679423p3679835.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Different result of multiple regression in R and SPSS
@Dimitri: I tried to enter it as numeric and still got the same outcome. I still wonder if there is any way to get the same result from both programs. @David, Bert: Yes, I found that the gender coefficient is R is exactly twice that of the one from SPSS. Need to study on parametrization. Thanks, Jay -- View this message in context: http://r.789695.n4.nabble.com/Different-result-of-multiple-regression-in-R-and-SPSS-tp3679423p3679590.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Different result of multiple regression in R and SPSS
First, it would have helped if you had posted the actual results for us to see how far they are off (and, more specifically, by which factor). Second, given your epiphany, you will find that that's exactly what David (and others before him) said or suggested. It is not about standardizing a nominal variable, which you theoretically cannot. It is about how the programs encode nominal variables by standard. Daniel J. wrote: > > I finally got the same result by converting "gender" variable as numeric, > and standardize it. > I guess SPSS automatically doing the same thing when doing analysis. > But, it still is not clear to me how I can interpret "standardized > categorical (dummy coded)" variable. > I'd rather stick to use R. > Thanks for all the comments and advice. > > Jay > -- View this message in context: http://r.789695.n4.nabble.com/Different-result-of-multiple-regression-in-R-and-SPSS-tp3679423p3679861.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Different result of multiple regression in R and SPSS
On 7/19/2011 4:04 PM, Bert Gunter wrote: On Tue, Jul 19, 2011 at 3:45 PM, David Winsemius wrote: On Jul 19, 2011, at 6:29 PM, J. wrote: Thanks for the answer. # However, I am still curious about which result I should use? The result from R or the one from SPSS? It is becoming apparent that you do not know how to use the results from either system. The progress of science would be safer if you get some advice from a person that knows what they are doing. ## I nominate this for an R fortune. -- Bert None of us ever know what we're doing at some level. We often think we do, and sometimes we get results more in spite of what we've done than because of it. That of course increases our confidence and encourages us to repeat mistakes in contexts where we might not be so lucky. Spencer Why the results from two programs are different? Different parametrizations. If I had to guess I would bet that the gender coefficient is R is exactly twice that of the one from SPSS. They are probably both correct in the context of their respective codings. -- David Winsemius, MD West Hartford, CT __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. -- Spencer Graves, PE, PhD President and Chief Technology Officer Structure Inspection and Monitoring, Inc. 751 Emerson Ct. San José, CA 95126 ph: 408-655-4567 web: www.structuremonitoring.com __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Different result of multiple regression in R and SPSS
> From: dwinsem...@comcast.net > To: seoulseoulse...@gmail.com > Date: Tue, 19 Jul 2011 18:45:47 -0400 > CC: r-help@r-project.org > Subject: Re: [R] Different result of multiple regression in R and SPSS > > > On Jul 19, 2011, at 6:29 PM, J. wrote: > > > Thanks for the answer. > > > > However, I am still curious about which result I should use? The > > result from > > R or the one from SPSS? > > It is becoming apparent that you do not know how to use the results > from either system. The progress of science would be safer if you get > some advice from a person that knows what they are doing. > > > Why the results from two programs are different? > > Different parametrizations. If I had to guess I would bet that the > gender coefficient is R is exactly twice that of the one from SPSS. > They are probably both correct in the context of their respective > codings. I guess I would also suggest, again, run some samples with known data sets and see what you get(RSSWKDSASWYG). You would want to do this anyway if you want to insure your real data is being used reasonably. You still need to have some way to check your opinion from the expert mentioned above and known data will help there too. A factor of 2 often shows up from just looking at pictures once you have some intuition. I've often been wrong on intuition, but chasing it down and proving it helps you learn a lot :) > > -- > David Winsemius, MD > West Hartford, CT > > __ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Different result of multiple regression in R and SPSS
On Tue, Jul 19, 2011 at 3:45 PM, David Winsemius wrote: > > On Jul 19, 2011, at 6:29 PM, J. wrote: > >> Thanks for the answer. >> # >> However, I am still curious about which result I should use? The result >> from >> R or the one from SPSS? > > It is becoming apparent that you do not know how to use the results from > either system. The progress of science would be safer if you get some advice > from a person that knows what they are doing. ## I nominate this for an R fortune. -- Bert > >> Why the results from two programs are different? > > Different parametrizations. If I had to guess I would bet that the gender > coefficient is R is exactly twice that of the one from SPSS. They are > probably both correct in the context of their respective codings. > > -- > David Winsemius, MD > West Hartford, CT > > __ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Different result of multiple regression in R and SPSS
On Jul 19, 2011, at 6:29 PM, J. wrote: Thanks for the answer. However, I am still curious about which result I should use? The result from R or the one from SPSS? It is becoming apparent that you do not know how to use the results from either system. The progress of science would be safer if you get some advice from a person that knows what they are doing. Why the results from two programs are different? Different parametrizations. If I had to guess I would bet that the gender coefficient is R is exactly twice that of the one from SPSS. They are probably both correct in the context of their respective codings. -- David Winsemius, MD West Hartford, CT __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Different result of multiple regression in R and SPSS
I don't think SPSS does anything with the variables you enter there. Have you entered it as numeric? Have you entered gender as numeric in R? On Tue, Jul 19, 2011 at 6:11 PM, Bert Gunter wrote: > Answer: Contrasts, i.e. the parameterization of the categorical variable(s) > df. > > ?contrasts may be of some help, but you really need to do some > background studying of the linear models principles involved. Googling > may provide tutorials. Also searching the mail archives, e.g.: > > https://stat.ethz.ch/pipermail/r-help/2009-February/187479.html > > -- Bert > > On Tue, Jul 19, 2011 at 2:39 PM, J. wrote: >> Hi, I am trying to do a simple multiple regression analysis that has one >> nominal variable (gender) and three numeric variables as independent >> variables and one numeric variable as dependent variable. >> >> So, I got a formula like this: >> summary(out.3 <- lm(scale(DV) ~ gender + scale(IV.1) + scale(IV.2) + >> scale(IV.3)) >> >> I tried to compare the outcome in R with the outcome in SPSS and found the >> results are different! >> I found that R and SPSS have the exact same outcome when every variable is >> numeric; however, whenever I included "gender (0/1)" variable in the >> equation, the result become different. >> >> I guess that SPSS automatically treat gender as a numeric variable and >> standardize it when running analysis. So, I tried to change "gender" to a >> numeric variable and ran analysis but the results were still not identical. >> >> What is the problem here and what is the right way to do this analysis? >> Thanks, >> >> Jay Yang >> >> -- >> View this message in context: >> http://r.789695.n4.nabble.com/Different-result-of-multiple-regression-in-R-and-SPSS-tp3679423p3679423.html >> Sent from the R help mailing list archive at Nabble.com. >> >> __ >> R-help@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. >> > > > > -- > "Men by nature long to get on to the ultimate truths, and will often > be impatient with elementary studies or fight shy of them. If it were > possible to reach the ultimate truths without the elementary studies > usually prefixed to them, these would not be preparatory studies but > superfluous diversions." > > -- Maimonides (1135-1204) > > Bert Gunter > Genentech Nonclinical Biostatistics > > __ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > -- Dimitri Liakhovitski marketfusionanalytics.com __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Different result of multiple regression in R and SPSS
Thanks for the answer. However, I am still curious about which result I should use? The result from R or the one from SPSS? Why the results from two programs are different? Jay -- View this message in context: http://r.789695.n4.nabble.com/Different-result-of-multiple-regression-in-R-and-SPSS-tp3679423p3679511.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Different result of multiple regression in R and SPSS
Answer: Contrasts, i.e. the parameterization of the categorical variable(s) df. ?contrasts may be of some help, but you really need to do some background studying of the linear models principles involved. Googling may provide tutorials. Also searching the mail archives, e.g.: https://stat.ethz.ch/pipermail/r-help/2009-February/187479.html -- Bert On Tue, Jul 19, 2011 at 2:39 PM, J. wrote: > Hi, I am trying to do a simple multiple regression analysis that has one > nominal variable (gender) and three numeric variables as independent > variables and one numeric variable as dependent variable. > > So, I got a formula like this: > summary(out.3 <- lm(scale(DV) ~ gender + scale(IV.1) + scale(IV.2) + > scale(IV.3)) > > I tried to compare the outcome in R with the outcome in SPSS and found the > results are different! > I found that R and SPSS have the exact same outcome when every variable is > numeric; however, whenever I included "gender (0/1)" variable in the > equation, the result become different. > > I guess that SPSS automatically treat gender as a numeric variable and > standardize it when running analysis. So, I tried to change "gender" to a > numeric variable and ran analysis but the results were still not identical. > > What is the problem here and what is the right way to do this analysis? > Thanks, > > Jay Yang > > -- > View this message in context: > http://r.789695.n4.nabble.com/Different-result-of-multiple-regression-in-R-and-SPSS-tp3679423p3679423.html > Sent from the R help mailing list archive at Nabble.com. > > __ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > -- "Men by nature long to get on to the ultimate truths, and will often be impatient with elementary studies or fight shy of them. If it were possible to reach the ultimate truths without the elementary studies usually prefixed to them, these would not be preparatory studies but superfluous diversions." -- Maimonides (1135-1204) Bert Gunter Genentech Nonclinical Biostatistics __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
[R] Different result of multiple regression in R and SPSS
Hi, I am trying to do a simple multiple regression analysis that has one nominal variable (gender) and three numeric variables as independent variables and one numeric variable as dependent variable. So, I got a formula like this: summary(out.3 <- lm(scale(DV) ~ gender + scale(IV.1) + scale(IV.2) + scale(IV.3)) I tried to compare the outcome in R with the outcome in SPSS and found the results are different! I found that R and SPSS have the exact same outcome when every variable is numeric; however, whenever I included "gender (0/1)" variable in the equation, the result become different. I guess that SPSS automatically treat gender as a numeric variable and standardize it when running analysis. So, I tried to change "gender" to a numeric variable and ran analysis but the results were still not identical. What is the problem here and what is the right way to do this analysis? Thanks, Jay Yang -- View this message in context: http://r.789695.n4.nabble.com/Different-result-of-multiple-regression-in-R-and-SPSS-tp3679423p3679423.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
