Non-critical versus Critical, continued

In the last post, the aggregate percentage was found to be dependent on the process parameters; however, when these were tightly maintained the product quality variation was negligible.  As it happens, the ELISA that was developed specifically for the cell line shows a dependence on the process parameters as well.  The latter of these are at the edge of statistical significance; however, a conservative approach was taken when building the model and they were included in the final analysis.
Parameter Estimates for CHO Host Cell Protein (HCP)

Term		Estimate	Std Error	t Ratio	Prob>|t|
Intercept		16.175041	0.876267	18.46	<.0001*
Load(93,312)		8.1260841	1.155147	7.03	0.0004*
Load cond(10,30)		-2.534245	1.18887	-2.13	0.0770
Load*Load cond		-3.252868	1.312414	-2.48	0.0479*

The simulator was then invoked using the same variances for the load and load conductivity that were applied in the previous post.  The ELISA assay is robust; however, the variance is a bit less.  Based upon the model fit, the root mean square error is about 2.75 ppm.  This is a pretty reasonable estimate of the method's error, so this was included in the assay's simulation.  A short time later and the model predicts quite a large variation in the ELISA when the process is operating under normal operating ranges.  As a result, variations in the ELISA results as a function of process variation are likely to be lost in the overall variation of the analytical result.
Model Simulation of CHO HCP as a Function of Load Amount and Load Conductivity

Based upon this information, and in conjunction with the data from the aggregate analysis, are the process parameters critical or not?