RAND IAQL Score Conversion Table

Table 1 RAND-IAQL T-Score Values and Standard Errors for Each Summed Score of the MARKS ASTHMA QUALITY OF LIFE QUESTIONNAIRE (AQLQ-Marks)
Summed Score Original AQLQ-Marks score RAND-IAQL scale T-score RAND-IAQL scale T-score SE
0 0 29.4 4.8
1 0.125 33.4 3.6
2 0.25 35.6 3.1
3 0.375 37.3 2.8
4 0.5 38.6 2.6
5 0.625 39.7 2.4
6 0.75 40.7 2.2
7 0.875 41.6 2.1
8 1 42.4 2.0
9 1.125 43.1 2.0
10 1.25 43.8 1.9
11 1.375 44.4 1.8
12 1.5 45.0 1.8
13 1.625 45.6 1.8
14 1.75 46.1 1.7
15 1.875 46.7 1.7
16 2 47.2 1.7
17 2.125 47.7 1.6
18 2.25 48.1 1.6
19 2.375 48.6 1.6
20 2.5 49.1 1.6
21 2.625 49.5 1.6
22 2.75 49.9 1.6
23 2.875 50.3 1.6
24 3 50.8 1.6
25 3.125 51.2 1.6
26 3.25 51.6 1.6
27 3.375 52.0 1.6
28 3.5 52.4 1.5
29 3.625 52.8 1.5
30 3.75 53.2 1.6
31 3.875 53.6 1.6
32 4 54.0 1.6
33 4.125 54.4 1.5
34 4.25 54.7 1.5
35 4.375 55.1 1.5
36 4.5 55.5 1.5
37 4.625 55.8 1.5
38 4.75 56.2 1.5
39 4.875 56.6 1.5
40 5 57.0 1.5
41 5.125 57.3 1.5
42 5.25 57.7 1.5
43 5.375 58.0 1.5
44 5.5 58.4 1.5
45 5.625 58.8 1.5
46 5.75 59.2 1.5
47 5.875 59.5 1.5
48 6 59.9 1.5
49 6.125 60.2 1.5
50 6.25 60.6 1.5
51 6.375 60.9 1.5
52 6.5 61.3 1.5
53 6.625 61.7 1.5
54 6.75 62.1 1.5
55 6.875 62.4 1.5
56 7 62.8 1.5
57 7.125 63.1 1.5
58 7.25 63.5 1.5
59 7.375 63.9 1.5
60 7.5 64.3 1.5
61 7.625 64.7 1.5
62 7.75 65.1 1.5
63 7.875 65.5 1.6
64 8 65.9 1.6
65 8.125 66.4 1.6
66 8.25 66.8 1.6
67 8.375 67.3 1.7
68 8.5 67.7 1.7
69 8.625 68.2 1.7
70 8.75 68.8 1.8
71 8.875 69.3 1.8
72 9 69.9 1.9
73 9.125 70.6 2.0
74 9.25 71.3 2.1
75 9.375 72.1 2.2
76 9.5 73.0 2.4
77 9.625 74.1 2.6
78 9.75 75.4 2.9
79 9.875 77.0 3.2
80 10 79.9 4.0

Note: T-score metric is a linear transformation from the IRT theta scale: T-score = 10 * theta + 50. SE in the table is the standard error on T-score metric.

This table was published in Clinical Therapeutics, Vol. 36, No.5, Edelen MO, Stucky B, Eberhart N, Lara M, Sherbourne CD. Correspondence between the RAND-Negative Impact of Asthma on Quality of Life Item Bank and the Marks Asthma Quality of Life Questionnaire. p. 686, Copyright Elsevier, 2014.

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