Figure 1.
Data distribution baseline pain VAS scores (average over 7 days).
Figure 2.
Data distribution follow-up pain VAS scores (average over 7 days).
Table 1.
Visual analogue scale distribution at baseline and follow-up (averaged over 7 days).
Table 2.
Visual analogue scale scores fit to the Rasch model.
Figure 3.
Person Item Threshold distribution (Pre VAS data).
The graph displays the person-item threshold distribution map with the x-axes displaying location or difficulty of item thresholds (lower half) and location or level of pain reported on the VAS by participants (upper half). The y-axes display the frequencies of item thresholds (lower half) and participants (upper half). Thresholds of seven items are shown and it can be seen that the thresholds spread over 1½ logits only.
Table 3.
Visual analogue scale item difficulty (pre-data).
Figure 4.
Item Response Curve for one VAS item.
The Item Response Curve displays the expected raw score on the y-axis and the interval transformed log score on the x-axis.
Table 4.
Vas conversion of raw (ordinal) data to interval data (item 4).
Figure 5.
Standardised Response Means displayed by baseline raw pain VAS score.
Inclusion criteria into the study included a minimum score on a single pain VAS of 30; although on the seven daily VAS measures some scored below 30 mm, these numbers were small. Standardised Response Means (SRM) data for those with daily measurs below 30 mm have therefore been combined into one group.