Analytical Quality by Design Approach of Reverse-Phase High-Performance Liquid Chromatography of Atorvastatin: Method Development, Optimization, Validation, and the Stability-Indicated Method

Table 3

Statistical ANOVA results for the responses (Y₁ = area; Y₂ = retention time; Y₃ = tailing factor).

Result (ANOVA)	Area	Retention time	Tailing factor
Regression
Sum of squares	23701247441	1.56	2.58
Degrees of freedom (df)	9	9	9
Mean squares	2633471938	0.17	0.28
F value	253.39	25.40	199.28
P	<0.0001	0.0002	<0.0001
Lack of fit tests
Sum of squares	55661902.75	0.01	0.004
Degrees of freedom (df)	3	3	3
Mean squares	18553967.58	0.002	0.002
F value	4.34	0.16	0.91
P	0.10	0.92	0.51
Residual
Sum of squares	72750482.75	0.05	0.01
Degrees of freedom (df)	7	7	7
Mean squares	10392926.11	0.01	0.001