Table 2. Visual analogue scale scores fit to the Rasch model.

Analysis number	Item fit residual		Person fit residual		χ2 interaction		PSI	Unidimensionality Independent t-test (95% CI)
	Mean	SD	Mean	SD	Value (df)	P
Baseline pain*
1*	0.078	1.403	−0.775	1.714	21.72 (14)	0.084	0.90	8.1% (5.3 to 11.0)
2∞	0.020	1.128	−0.580	1.366	15.40 (14)	0.351	0.90	7.3% (4.3 to 10.3)
Post Pain
3†	−3.304	2.190	−1.507	1.912	21.37 (14)	0.092	0.99	8.7% (5.6 to 11.7)
4∼	−0.849	0.755	−0.803	1.213	4.952 (6)	0.550	0.91	3.1% (0 to 6.1)

* Baseline pain: seven daily measures of pain on a VAS before the commencement of the trial, all cases included in the data set.

^∞Baseline pain: seven daily measures of pain on a VAS before the commencement of the trial, 15 misfitting cases have been excluded.

^†Post pain contains seven daily measures of pain on a VAS after the completion of the trial, item threshold shave been anchored to baseline item thresholds, 15 misfitting cases have been excluded.

^∼Post pain contains three daily measures of pain on a VAS after the completion of the trial, item threshold shave been anchored to baseline item thresholds, 15 misfitting cases have been excluded and 4 items have been deleted.