Descriptive statistics were used to summarise qualitative data, while multivariate regression analyses were used to assess the association between selected outcomes and a number of hypothetical predictors.
Furthermore, we considered FEV1% as a potential predictor of the respiratory symptom score, and both FEV1% and the respiratory symptom score as hypothetical predictors of quality of life.
The prognostic index value for a given individual summarises the relative hazard of that person with respect to a hypothetical patient with predictor values all equal to zero.
The first table shows the hypothetical distribution of subjects according to the predictors and outcomes (Table 1).
To further illustrate the application of this approach, we ran additional logistic regression models that were fitted with alcohol use as the only predictor (univariate model), thereby creating a hypothetical scenario where all potential confounding factors were unknown.
In this population-based sample (including over-representation of lower socioeconomic groupings), the main predictors of intention to attend a hypothetical eye health test were Attitude, Perceived control over attendance, Anticipated regret if did not attend and black ethnicity.
Further, as shown in Web Appendix D, the distribution of Y given in the hypothetical population of complete clusters depends on which predictors are included in the model for the expected number with, and there is no obvious reason to prefer one set of predictors to any other.
AIC model selection considered in the context of hypothetical predictions supports island area as the most important predictor of body size (Table 2; Fig. 3).
Univariate analysis identified no significant predictors of willingness to participate in the hypothetical stroke study.
Cumulative costs over time will be calculated using standardized methods,[ 64, 65]and costs for average hypothetical patients will be calculated using the least squares means method, and adjusted for significant predictor variables for costs for medical and wait-listed controls.
