Table 1.

Asthma symptom study attributes and levels; McKenzie et al. [24].

Attributes	Attribute levels	Coded levels
x1: Cough	No cough	0
	Some coughing but no restricted activities	1
	A lot of coughing with restricted activities	2
x2: Breathlessness	No breathlessness	0
	A little breathlessness but no restricted activities	1
	Very breathlessness with restricted activities	2
x3: Wheeze	No wheeze	0
	Some wheezing but no restricted activities	1
	Very wheezy with restricted activities	2
x4: Chest tightness	Chest not tight	0
	A little tightness	1
	Chest very tight	2
x5: Sleep disturbance	No sleep disturbance	0
	Awoke once with cough/breathlessness	1
	Awoke 2–3 times with cough/breathlessness	2