Locate Original Source 11, “Driving impairment due to sleepiness is exacerbated by low alcohol in­take.” It is not on the companion website but may be available at www.ncbi.nlm.nih.gov/pmc/www.ncbi.nlm.nih.gov/pmc/articles/PMC1740622/pdf/v60p00689.pdf.Find the description of how the researchers measured “subjective sleepiness.”
a. Explain how “subjective sleepiness” was measured.
b. Was “subjective sleepiness” measured as a nominal, ordinal, or measurement variable? Explain.