Estimates of population values will be derived by standard methods for analysing a multistage cluster sample.
Utility values will be derived using Brazier's algorithm [ 75, 76].
Utility values will be derived from the EQ-5D and from the SF-36 using the algorithm provided by the SF-6D.
At baseline (the pre-operative assessment) and each follow-up point, simple 10 cm visual analogue scales (VAS) will be used to record least and usual back and leg pain, from which average values will be derived [ 58].
Additionally, a cost-utility analysis will be performed to enable comparisons to be drawn with other areas of health care; utility will be measured using QALY values, which will be derived separately from (i) the EuroQoL EQ5D, and (ii) the SF-12 SF-6D.
Since the "value" of such letters involves as much the romantic element of the actual paper that the writer once touched, and the scrawl that she or he has left on that page, the gaveler might justifiably question what value and pleasure will be derived from the auctioning of CD's and flash drives.
At the end, reliable estimators of the diagnostic accuracy (sensitivity, specificity, predictive value, limits of the test) will be derived from the trial.
19 Data (eg, NHS resource use and costs, service model efficacy, event and risk probabilities and utility values) for the economic model will be derived from the literature review, from the DCE interviews, from retrospective retrieval of hospital and general practitioner records and from clinical experts.
RAI will be evaluated as a diagnostic test and sensitivity, specificity, positive predictive value, negative predictive value, likelihood ratios, and receiver operating characteristics (ROCs) will be derived.
