Table 5.

Transformation of raw (ordinal) score to interval score

Raw score	Interval score
0	0
1	2.63
2	4.50
3	5.84
4	6.90
5	7.80
6	8.60
7	9.32
8	10.00
9	10.64
10	11.26
11	11.86
12	12.45
13	13.03
14	13.62
15	14.22
16	14.84
17	15.48
18	16.17
19	16.92
20	17.76
21	18.75
22	19.96
23	21.65
24	24.00