RAND-IAQL-4 Scoring Procedure and Translation Table

Scoring Procedure

Each of the four items on the RAND-IAQL-4 use five-category response options ranging in value from 0 to 4. Higher scores indicate greater negative impact of asthma on quality of life. In cases where the items have been administered on a range 1 to 5, first re-score response options for each item to 0 to 4 (e.g., 1=0, 2=1, 3=2, 4=3, 5=4). To find the total raw score, sum across the values of the responses to all four questions. The lowest possible score will be 0 and the highest possible score will be 16. If any of the four items are missing, assign the respondent a missing value for the total score.

Next, based on a given total score, find the associated IRT-score in the “T-Score” column. The “T-Score” column provides the IRT-based asthma quality of life score score estimate given each particular total score. Note that the “T-Score” and “SE” columns transform the IRT metric (N(mean=0, standard deviation =1)) to a T-score metric (mean = 50, standard deviation = 10). A higher T-score means worse Asthma quality of life.

RAND-IAQL Main Page

References

Thissen, D., Pommerich, M., Billeaud, K., & Williams, V.S.L. (1995). Item response theory for scores on tests including polytomous items with ordered responses. Applied Psychological Measurement, 19, 39-49.

Thissen, D., Nelson, L., Rosa, K., & McLeod, L.D. (2001). Item response theory for items scored in more than two categories. In D. Thissen & H. Wainer (Eds), Test Scoring (pp. 141-186). Mahwah, NJ: Lawrence Erlbaum Associates.

Scoring Table

Sum Score	T-Score	SE
0	36.2	5.7
1	41.8	4.0
2	45.1	3.4
3	47.5	3.1
4	49.4	3.0
5	51.1	2.9
6	52.7	2.8
7	54.2	2.8
8	55.6	2.8
9	57.0	2.7
10	58.4	2.7
11	59.8	2.7
12	61.3	2.8
13	62.9	2.9
14	64.7	3.1
15	66.9	3.3
16	71.3	4.6
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.