The California Air Resources Board's air quality monitoring program collects accurate real-time measurements of ambient level pollutants at 40 monitoring sites located throughout the state. One typical measurement used to assess air quality is the concentration of particulate matter less or equal than 2.5 μm in diameter (PM2.5). Concentrations of PM2.5 greater than 10 g/m3 are considered dangerous to human health. Daily measurements of PM2.5 at the monitoring sites are collected at 3 random times during the day. Answer the following questions:
Identify the variable and the unit of measurement.
Is the variable quantitative or qualitative?
What is the implied population?
Is the variable random?
What factors can contribute to the random nature of the variable in question? In other words, what are some sources of variability and uncertainty in the variable?
How does the sampling scheme try to capture and account for the variability in the random variable?
Describe one source of variability that the above sampling is not capturing. How would you design this observational study to capture this source of variability?
