In summary, evaluation of NLG texts in the past has primarily been done using human subjects, either by measuring the impact of texts on task performance, or by asking subjects to rate texts.
the other method is an algorithm which is based on a spreadsheet and flowchart which one of the forecasters gave to the SUMtIME team at the beginning of the project (Reiter, Sripada, and Robertson 2003, page 499); a simplified version of this algorithm is presented in Figure 4.