eldo_user

Statistical Experimental Design and Analysis
Defining the Levels of Factors for the DEX Analysis
Defining the Levels of Factors for the DEX Analysis
The Eldo .PARAMDEX command statement is used to specify the levels of factors, including
the normal and uniform distributions. The .PARAMDEX command is also used to specify
levels of factors with respect to the standard deviation and half ranges of these distributions, and
with respect to the nominal value for both noise and control factors.
Note
When writing levels for factors within .PARAMDEX statements, extreme values may give
runs that are not feasible. These runs are simply ignored during post-analysis of the
experiment.
Tip
See “.PARAMDEX” in the Eldo Reference Manual.
This topic is divided into:
Defining Levels for Noise Factors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 565
Defining Levels With Respect to the Nominal Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . 570
Defining Levels for Noise Factors
For noise factors, the .PARAMDEX command statement is directly related to the statistical data
defined in the .PARAM statement.
The levels information is extracted from the arguments of the .PARAM statement:
.PARAM PARAMETER_NAME=EXPRESSION
+ {LOT|DEV|DEVX}[/GAUSS|/UNIFORM] = RVALUE|RVALUE%
The value EXPRESSION defines the nominal value x nom , or the mean value, for the normal and
uniform distributions. The value RVALUE represents the standard deviation σ for the normal
distribution and the half-range for the uniform distribution.
Note
In Eldo, the definition of the standard deviation σ for the uniform distribution is not correct
from a statistical point of view. There is confusion between the standard deviation and the
range of the distribution.
For coherency, the DEX analysis uses the proper definition of this statistical value, with
arguments SIG and RNG available for factors associated with uniform distributions.
Eldo® User's Manual, 15.3 565