Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Three factors and three levels of response surface methodology.
| Factor | Levels | ||
|---|---|---|---|
| Soaking time (h) X1 | 0(−1) | 3(0) | 6(1) |
| Extraction time (h) X2 | 3(−1) | 6(0) | 9(1) |
| Ratio of liquid to solid (mL/g) X3 | 8(−1) | 10(0) | 12(1) |
(−1), (0) and (1) were coded levels.
