Figure 2. Bland-Altman plot indicating agreement between PSG and THIM-SOL on night 2 for study 1 data.

The solid black line indicates the mean difference, the dotted red lines indicate the upper and lower limits of agreement, and the dotted blue line is the linear trendline. The R² value and P value represent the linear regression line as indicators of the degree of proportional bias. Some datapoints represent many overlapping values. PSG = polysomnography, SD = standard deviation, SOL = sleep onset latency.