Table 1.

The number of items proceeding to each step of the analysis The number of and examples of items removed at each stage of the psychometric analysis.

Stage of analysis	Number of items removed	Reason for removal	Examples
	1	Concerns about the way the item was presented
(a)	28	< 10% or > 90% of responses in 'cannot'	Reaching for a cup and taking a sip of water Combing hair at a sink Cycling on a heavily laden bicycle
(b)	26	Significant difference between M and F and/or under and over 85 years	Washing up (easier for older respondents) Crossing the street (easier for younger respondents Preparing a warm meal (easier for female respondents)
(c)	26	Item fit p-value < 0.01 or estimates of βi not stable	Taking oral medication Cycling Getting money out of the bank using an ATM
In item bank	79		See Table 2
Total	160