tag:blogger.com,1999:blog-6710487119650146215.post2339830260901121974..comments2017-03-27T01:51:05.632-07:00Comments on R Tutorial Series: R Tutorial Series: Two-Way ANOVA with Unequal Sample SizesJohnhttp://www.blogger.com/profile/05331039307550313006noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-6710487119650146215.post-15943179418501553632013-03-26T17:01:45.858-07:002013-03-26T17:01:45.858-07:00Is this the same procedure for MANOVA with unequa ...Is this the same procedure for MANOVA with unequa sample sizes?<br /><br />Thank you <br /><br />ChristosChristos Giannoulishttp://www.blogger.com/profile/02183614966607062761noreply@blogger.comtag:blogger.com,1999:blog-6710487119650146215.post-67322133763214149012011-03-01T07:55:00.921-07:002011-03-01T07:55:00.921-07:00Hi Ruediger,
Thanks for the website and paper re...Hi Ruediger, <br /><br />Thanks for the website and paper reference.<br /><br />JohnJohn M. Quickhttp://www.blogger.com/profile/05331039307550313006noreply@blogger.comtag:blogger.com,1999:blog-6710487119650146215.post-54262420722530566352011-03-01T05:46:04.241-07:002011-03-01T05:46:04.241-07:00for good explanations, look at Falk Scholer's ...for good explanations, look at Falk Scholer's site:<br />http://goanna.cs.rmit.edu.au/~fscholer/anova.php<br /><br />and the paper by Ista Zahn, referenced there.Ruedigerhttp://www.leuphana.de/en/hans-ruediger-pfister.htmlnoreply@blogger.comtag:blogger.com,1999:blog-6710487119650146215.post-69084519811944248982011-02-28T19:22:11.224-07:002011-02-28T19:22:11.224-07:00Hi,
Thanks for the feedback. Unfortunately, I'...Hi,<br /><br />Thanks for the feedback. Unfortunately, I'm not an expert on statistical methods nor am I qualified to offer statistical advice. The process of using weighted means with Type I SS and unweighted means with Type III SS for unequal sample sizes was taught to me in an ANOVA course for social scientists. I am not familiar with the use of Type II SS.<br /><br />I recommend talking to a professional statistician about the merits and circumstances surrounding the different tests. You should also consult a senior member of your field and the published research, since different fields often have different standards and procedures for handling statistics.John M. Quickhttp://www.blogger.com/profile/05331039307550313006noreply@blogger.comtag:blogger.com,1999:blog-6710487119650146215.post-58424372086491588572011-02-28T16:55:53.836-07:002011-02-28T16:55:53.836-07:00Hi, thanks for this post.
I think it would be hel...Hi, thanks for this post.<br /><br />I think it would be helpful to explain the different questions answered using the different Type I vs Type III analyses.<br /><br />Can you see any use for Type II SS?<br />Perhaps when a priori no interaction is expected?ane handles manhttp://www.blogger.com/profile/07863739093681446569noreply@blogger.comtag:blogger.com,1999:blog-6710487119650146215.post-62190728294573927282011-02-28T12:45:43.862-07:002011-02-28T12:45:43.862-07:00Hi. Thanks for the tip, but I get the same results...Hi. Thanks for the tip, but I get the same results using what is provided in the tutorial:<br /><br />Anova(lm(math ~ environment * instruction, dataTwoWayUnequalSample), type = "3")<br /><br />and your suggestion: <br /><br />Anova(lm(math ~ environment * instruction, dataTwoWayUnequalSample), type = "3",contrasts=list(environment=contr.sum, instruction=contr.sum))<br /><br />Can you be more specific about the differences between the functions and how they impact the results?<br /><br />Thanks,<br />JohnJohn M. Quickhttp://www.blogger.com/profile/05331039307550313006noreply@blogger.comtag:blogger.com,1999:blog-6710487119650146215.post-59350342386293042872011-02-28T12:35:48.427-07:002011-02-28T12:35:48.427-07:00Anova(lm(...), type="III") will not give...Anova(lm(...), type="III") will not give SS type III unless one also sets options(contrasts=c(unordered="contr.sum", ordered="contr.poly")) beforehand, or uses Anova(lm(..., contrasts=list(environment=contr.sum, instruction=contr.sum))).Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6710487119650146215.post-80823520836831719482011-02-28T11:34:26.660-07:002011-02-28T11:34:26.660-07:00Type III sum of squares? I start think about John ...Type III sum of squares? I start think about John Maindonald!Anonymousnoreply@blogger.com