Re: [R] help with statistics in R - how to measure the effect of users in groups

2011-10-10 Thread gj
Hi Petr, It's not an equation. It's my mistake; the * are meant to be field separators for the example data. I should have just use blank spaces as follows: users Group1 Group2 Group3 u110 5N/A u2 6 N/A 4 u3 5 2

Re: [R] help with statistics in R - how to measure the effect of users in groups

2011-10-10 Thread Petr PIKAL
Hi Petr, It's not an equation. It's my mistake; the * are meant to be field separators for the example data. I should have just use blank spaces as follows: users Group1 Group2 Group3 u110 5N/A u2 6 N/A 4 u3 5

Re: [R] help with statistics in R - how to measure the effect of users in groups

2011-10-10 Thread gj
Thanks Petr. I will try it on the real data. But that will only show that the groups are different or not. Is there any way I can test if the users are different when they are in different groups? Regards Gawesh On Mon, Oct 10, 2011 at 11:17 AM, Petr PIKAL petr.pi...@precheza.cz wrote: Hi

Re: [R] help with statistics in R - how to measure the effect of users in groups

2011-10-10 Thread Carlos Ortega
Hello, In package qualityTools you can find one way to perform this analysis through the gageRR() function. The effect of an operator on the mesasurement system (Reproductibility) is to me equivalent to the effect you try to study of your users when they are in different groups. Regards, Carlos

Re: [R] help with statistics in R - how to measure the effect of users in groups

2011-10-10 Thread Bert Gunter
Assuming your data are in a data frame, yourdat, as: User Group Value u1 1 !0 u2 2 5 u3 3 NA ...(etc) where Group is **explicitly coerced to be a factor,** then you want the User x Group interaction, obtained from lm( Value ~ Group*User,data = yourdat)

Re: [R] help with statistics in R - how to measure the effect of users in groups

2011-10-10 Thread Bert Gunter
I should have added... If your design is not nearly balanced, main effects and interactions will not have any natural interpretation because they will be (partially) confounded. (I realize nearly is not a very useful characterization, but I do not know a better one, as it probably depends on the

Re: [R] help with statistics in R - how to measure the effect of users in groups

2011-10-10 Thread Anupam
Groups are different treatments given to Users for your Outcome (measurement) of interest. Take this idea forward and you will have an answer. Anupam. -Original Message- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of Bert Gunter Sent: Monday,

Re: [R] help with statistics in R - how to measure the effect of users in groups

2011-10-10 Thread gj
Hi Bert, The real situation is like what you suggested, user x group interactions. The users can be in more than one group. In fact, the data that I am trying to analyse constitute of users, online forums as groups and the attribute under measure is the number of posts made by each user in a

Re: [R] help with statistics in R - how to measure the effect of users in groups

2011-10-10 Thread Bert Gunter
OK. So my original advice and warnings are correct. However, now there is an additional wrinkle because your response is a count, which is not a continuous measurement. For this, you'll need glm(..., family = poisson) instead of lm(...), where the ... is the stuff I gave you before. A backup

Re: [R] help with statistics in R - how to measure the effect of users in groups

2011-10-10 Thread Petr PIKAL
Hi I would try either some tree method (mvpart) or you can expand lm model also with users. fit-lm(value~variable+users, data=test.m) Anyway I am not an ultimate expert in statistics. so you shall also consult some appropriate literature which can be found in CRAN web. Did you try to look

Re: [R] help with statistics in R - how to measure the effect of users in groups

2011-10-10 Thread Petr PIKAL
Hi OK. So my original advice and warnings are correct. However, now there is an additional wrinkle because your response is a count, which is not a continuous measurement. For this, you'll need glm(..., family = poisson) instead of lm(...), where the ... is the stuff I gave you before.

[R] help with statistics in R - how to measure the effect of users in groups

2011-10-09 Thread gj
Hi, I'm a newbie to R. My knowledge of statistics is mostly self-taught. My problem is how to measure the effect of users in groups. I can calculate a particular attribute for a user in a group. But my hypothesis is that the user's attribute is not independent of each other and that the user's