The relationship between <i>PVT standard deviation</i> and <i>PVT mean</i>.

<p>Data are shown for Chronic Sleep Restriction (CSR) and Control conditions. Data from both conditions demonstrate a robust relationship between the standard deviation and mean of the Psychomotor Vigilance Task (PVT). Logarithms of each variables are plotted to the wide ranges that the data span. Each data point represents one 10-min session. The same polynomial fit is shown to data in both plots with 95% confidence intervals indicated by dashed lines.