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I am relatively new to the study of statistics. I did this problem in excel. I thought I would compare to MathCAD. What am I doing wrong?
Thanks for any help or direction on how to use/interpret MathCADs Anova function.
Matt
Hello!
Look in the help file "Mathcad Help" (F1) for the keyword "anova". There you can find examples of the work function "anova".
Also you can install the e-book "Practical Statistics" (there also it is possible to find examples of the ANOVA analysis). You can download it here: http://communities.ptc.com/docs/DOC-1611
I was originally confused by the design matrix A and its dimensions. After rereading the MathCAD help you mentioned I noticed that 'A' to number of runs of data. It was initially confusing since MathCADs help used an example that had 5 sets of data with 5 replicates. A nights sleep and a new look as brought insight.
Thanks
Matt
You need to fix your setup for the analysis to work. First you need to recognize that your Y should be 15x1 not 5x3. Your X is a choice of A, B or C varieties but has to be parameterized. One way to do this is by using a value plus 2 indicator functions (= 0 or 1). It will help if you write out the model equation (everything in statistics needs a model equation). Y = beta0 + beta1*A + beta2*B + error where A = 1 if type A, 0 otherwise; B = 1 if type B, 0 otherwise; and type C has both A=0 and B = 0. This gives us 3 types using 2 parameters.
Your X then is a 15x3 where the first column is all 1's, 2nd column is the indicators for Atype, 3rd column is the indicators for Btype. The equation in matrix notation looks like Y = X * Beta and you solve for Beta. Note that Beta is 3x1