Table 3.

Regression analysis for  % triterpenoid extraction from Swertia chirata using Plackett–Burman design criterion

Term	Effect	Coefficient	SE coefficient	T	P
Constant	−	3.0058	0.06731	44.65	0.000
Temperature	0.4417	0.2208	0.06731	3.28	0.017
Time	− 0.1783	− 0.0892	0.06731	− 1.32	0.234
Solvent composition	0.3683	0.1842	0.06731	2.74	0.034
Solid–solvent ratio	0.0317	0.0158	0.06731	0.24	0.822
Particle size	− 0.6417	− 0.3208	0.06731	− 4.77	0.003