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Re: discriminant analysis: How do I test for stat. significance?
Posted:
Nov 10, 2006 5:15 AM


holg wrote: > Hi, > > I have conducted a discriminant analysis using two separate sets of > independent variables for classification of 300 images falling into > three categories. How do I test for statistical significance when SPSS > tells me, that for the one set of parameters, 71% of images, for the > other 81% were classified correctly? > > Best wishes, > Holg
If nothing else is available you could do the obvious. That is: (i) choose a test statistic (possibly the % figure, possible some measure of distance between categories); (ii) evaluate a distribution for the test statistic under the null hypothesis (which is presumably that categories can't be predicted from the "parameters") ... do this by generating ramdomised sets of data using your observed data as the basis of this ... randomly reassign images to categories, keeping the numbers in each category the same ... for each randomised dataset reapply the discriminant analysis and extract the test statistic for each. You may only need to do 10 or so randomised datasets to get a good enough idea of the significance of your original test statistic, or more if you need to do some formal reporting (100200 say).
David Jones



