Segmented Linear Regression Modelling of Time-Series of Binary Variables in Healthcare

Figure 4

Modelling of the time-series of 365-day mortality. Solid red line is the best model. Solid black lines are the other models. Dashed vertical line is the onset of the HFU. Data values are not shown as they are points at either y = 0 or 1. (i) Plateau model  = 0.2144. (ii) Line model  = −0.000037t + 0.2481. (iii) Line-plateau model  = −0.000047t + 0.2549 for t = 0 to 1711 days and  = 0.1912 for t = 1711 to 1747.4 days (iv) Line-line model  = −0.000054t + 0.2580 for t = 0 to 1583.3 days and  = 0.000460 (t − 1583.3) + 0.1834 for t = 1583.3 to 1747.4 days.