01-04-2012 07:46 AM
I am working on a task concerning nested procedures.
The input is as follows:
input lot wafer site rho;
1 1 1 4.289
Then I use the following commands:
by lot wafer site;
class lot wafer site;
As output, I get the 'Nested random effects analysis of variance for variable rho'.
But the output shows some dots, for example: Variance source Site: There is a dot in the column of 'random sum of squares' in 'F value' and in 'Pr>F'.
Also in variance source Error, there are only dots or zeros.
Can anyone tell me why these dots are there?? And how I can get them away? => How can I solve this problem?
Thanks in advance and best regards,
01-04-2012 08:11 AM
The first thing that I would think of would be incomplete data, so that all degrees of freedom are used. I would guess that there is only one observation per site within wafer within lot--hence no residual variability and no variance due to site. What happens if you fit:
class lot wafer;
The residual error in this case will be due to site within wafer within lot.