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I have a question about how to filter the data frame: Suppose my data frame has variables like gender, age,... How to get a subset of the data frame, with only female (or male) and/or age > 50...? What is the typical syntax? I tried several condition expressions, but none of them worked... Thanks a lot! -- View this message in context:

I have a simple regression using lm(). If I just want to check the coefficient, I can use summary(lm())$coef; if I need the standard error, I can use summary(lm())$s, if I need the residuals, I can use summary(lm())$res. OK. How can I get the R-squares and Adjusted R-squares using $...? Is there a function, like objects(), that can show all the references for values? Thanks a lot! -- View this

I have a question. I have a data set (about 100,000 observations). How would I get the distribution curve graph? This is like, if I use hist(x, freq="TRUE", breaks=1000) to get the histogram, now the question is, I don't need the histogram itself, I just need the curve that connects the top of each histogram bin. Thank you very much! -- View this message in context:

X and Y are independently distributed random variables. I would like to study the contours of the joint density of these two variables. Any function to call? Thank you very much! -- View this message in context: http://www.nabble.com/How-to-plot-contours-for-joint-density-of-2-independently-distributed-r.v.--tp19493126p19493126.html Sent from the R help mailing list archive at Nabble.com.

How to get robust M-estimators of multivariate scatter using Huber's psi? Which package/function should I look into? Ideally, I hope I can self-define thresholds of Huber's psi function. Thanks a lot!!! -- View this message in context: http://www.nabble.com/How-to-get-robust-M-estimator-of-multivariate-scatter-using-Huber%27s-psi--tp20585755p20585755.html Sent from the R help mailing

I know, this is a forum about R. But I am so desperate of this problem (BTW, anyone knows any good Statistics/Math forum to post question like this?): A and B are both n x n positive definite matrix. Denote A > B, if A - B is positive definite. I know this is true: if A > B, then A^{-1} < B^{-1}. But how to prove this? I tried to diagonalize A and B, but since they can have different