To ensure that your results are valid, consider the following guidelines when you perform the analysis and interpret your results.
Perform a stability study first
You must perform Stability
Study before you can predict responses for new observations.
Verify that the model meets the assumptions of the analysis
If the model does not meet the assumptions of the original analysis, the predictions can be inaccurate.
The values of the variables should be within the range of the data that you used to fit the model
Be cautious when you extend predictions beyond the original data because you cannot be certain that the relationships remain consistent. For example, a medication could lose strength more rapidly after the point at which your data ends. Only further testing with older samples can confirm that your shelf life estimate is accurate.