Comments on: loess and lowess and locfit, oh my http://hea-www.harvard.edu/AstroStat/slog/2008/question-locfit-errors/ Weaving together Astronomy+Statistics+Computer Science+Engineering+Intrumentation, far beyond the growing borders Fri, 01 Jun 2012 18:47:52 +0000 hourly 1 http://wordpress.org/?v=3.4 By: vlk http://hea-www.harvard.edu/AstroStat/slog/2008/question-locfit-errors/comment-page-1/#comment-318 vlk Sat, 16 Aug 2008 22:51:39 +0000 http://hea-www.harvard.edu/AstroStat/slog/?p=391#comment-318 See <a href="http://cxc.harvard.edu/proposer/POG/html/chap4.html#tth_sEc4.2.2" rel="nofollow">Fig 4.2 (lower panel)</a> in the Chandra Proposer's Observatory Guide. The data shown there are similar to those that Diab and Ping are considering. There is an unexplained discrepancy between SSD and FPC points (never mind what the acronyms mean; they are measurements of the same thing with different instruments) that need to be "spliced" smoothly after making suitable post-hoc adjustments. See Fig 4.2 (lower panel) in the Chandra Proposer’s Observatory Guide. The data shown there are similar to those that Diab and Ping are considering. There is an unexplained discrepancy between SSD and FPC points (never mind what the acronyms mean; they are measurements of the same thing with different instruments) that need to be “spliced” smoothly after making suitable post-hoc adjustments.

]]> By: hlee http://hea-www.harvard.edu/AstroStat/slog/2008/question-locfit-errors/comment-page-1/#comment-317 hlee Sat, 16 Aug 2008 00:51:43 +0000 http://hea-www.harvard.edu/AstroStat/slog/?p=391#comment-317 To get comments or suggestions from statisticians, it would be easier if you show a plot of data (response vs. predictors) on which locfit or loess is applied. Depending on data and the objective of the study, various approaches to local regression or smoothing are available. It'll be nice to show people the looks of measurement errors (how they are associated with data) as well as two sets (approaching from a mixture model of two components or just providing proportions to pool the uncertainty) to derive the appropriate model. Graphics for diagnostics and modeling direction/assumption prior to any comments. To get comments or suggestions from statisticians, it would be easier if you show a plot of data (response vs. predictors) on which locfit or loess is applied. Depending on data and the objective of the study, various approaches to local regression or smoothing are available. It’ll be nice to show people the looks of measurement errors (how they are associated with data) as well as two sets (approaching from a mixture model of two components or just providing proportions to pool the uncertainty) to derive the appropriate model.

Graphics for diagnostics and modeling direction/assumption prior to any comments.

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