Factor

Symbol

−1

0

+1

−1.68

+1.68

Temperature (˚C)

X1

30

40

50

23

56.8

Time (days)

X2

3

6

9

1

11

pH

X3

4

6

8

2.6

9.3

No of core points nj

8

No of starlike points nα

6

No of null points no

6

Total no of points n

20