On Mon, Jun 29, 2009 at 10:22:15PM -0400, Robert Haas wrote: > I'm finding myself unable to follow all the terminology on this thead. > What's dimension reduction?
For instance, ask a bunch of people a bunch of survey questions, in hopes of predicting some value (for instance, whether or not these people will die of a heart attack in the next three years). After waiting three years, discover that some of the questions didn't really help you predict the outcome. Remove them from the dataset. That's dimension reduction. > What's PCA? Principal Component Analysis, http://en.wikipedia.org/wiki/Principal_components_analysis -- Josh / eggyknap End Point, Corp. http://www.endpoint.com
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