Re: [R] add a point to regression line and cook's distance

2003-12-04 Thread Tony Plate
One way of implementing some Bayesian techniques is to add data points based on prior knowledge. E.g., see Gelman, Carlin, Stern Rubin, in Bayesian Data Analysis (1997) for how a prior on a regression parameter can be interpreted as an additional data point. (Section 8.9 in my 2000

Re: [R] add a point to regression line and cook's distance

2003-12-03 Thread Spencer Graves
What is the context? What do the outliers represent? If you think carefully about the context, you may find the answer. hope this helps. spencer graves p.s. I know statisticians who worked for HP before the split and who still work for either HP or Agilent, I'm not certain which.

RE: [R] add a point to regression line and cook's distance

2003-12-03 Thread Wiener, Matthew
If you know that the line should pass through (0,0), would it make sense to do a regression without an intercept? You can do that by putting -1 in the formula, like: lm(y ~ x - 1). Hope this helps, Matt Matthew Wiener RY84-202 Applied Computer Science Mathematics Dept. Merck Research Labs

Re: [R] add a point to regression line and cook's distance

2003-12-03 Thread Murray Jorgensen
Not a good idea, unless the regression function is *known* to be linear. More likely it is only approximately linear over small ranges. Murray Jorgensen Wiener, Matthew wrote: If you know that the line should pass through (0,0), would it make sense to do a regression without an intercept? You

RE: [R] add a point to regression line and cook's distance

2003-12-03 Thread jonathan_li
It is likely that the true relationship is nonlinear. There isn't a priori knowledge about linearity. In the small range where we do have enough data, the relationship looks linear. Outside the range, the data are very scarse and have high level of noises too. This is why adding (0,0) to the

Re: [R] add a point to regression line and cook's distance

2003-12-03 Thread Jason Turner
[EMAIL PROTECTED] wrote: Hi, MY question is like the following: I would like to have a robust regression line. The data I have are mostly clustered around a small range. So the regression line tend to be influenced strongly by outlier points (with large cook's distance). From the