| Coded variables (Xi) | Factors (Ui) | Experimental field | |
| Min value | Max value | ||
| Screening | |||
| X1 | Temperature (U1) | 30˚C | 80˚C |
| X2 | Stirring speed (U2) | 300 rpm | 1100 rpm |
| X3 | Reaction time (U3) | 45 min | 145 min |
| X4 | type of alcohol (U4) | EtOH | MeOH |
| X5 | Type of catalyst (U5) | H2SO4 | KOH |
| Full factorial design | |||
| X1 | Temperature (U1) | 70˚C | 90˚C |
| X2 | Stirring speed (U2) | 100 rpm | 300 rpm |
| X3 | Reaction time (U3) | 125 min | 165 min |
| X4 | type of alcohol (U4) | EtOH | |
| X5 | Type of catalyst (U5) | H2SO4 | |
| Central composite design | |||
| X1 | Temperature (U1) | 90˚C | |
| X2 | Stirring speed (U2) | 200 rpm | 400 rpm |
| X3 | Reaction time (U3) | 105 min | 145 min |
| X4 | type of alcohol (U4) | EtOH | |
| X5 | Type of catalyst (U5) | H2SO4 | |