Fig. 3.

Review of base-case methods used to handle missing cost and effect data between 2003–2009 and 2009–2015. Legend: complete case analysis (CCA), last value carried forward (LVCF), linear extrapolation (Lin Ext), mean imputation (Mean), conditional imputation (Cond), multiple imputation (MI), any other method present in fewer than four articles (Others), unspecified method (Unclear). The category “Unclear” includes those articles for which it was not possible, based on the text, to understand the methodology used to deal with the missingness, while the category “Others” consists of the following methods: random draw, linear mixed-effects model, expectation-maximisation algorithm, input-case analysis, assumed zeros, two-part regression. The numbers to the right of the bars in the graphs are the number of papers including the corresponding method in the base-case analysis