Among energy demands of economic sectors of a country, industrial
energy consumption is one of the hardest end-uses to
analyze, model, and forecast. The structure of energy demand for an
entire industrial sector is unclear. For example, the energy demand
of the industrial sector might not be strongly correlated with
population size because industrial products may be sold in domestic
markets or exported to global markets. To describe how the
dependent variable (energy demand in industrial sector) and independent
variables (such as prices of energy carriers) interact
with each other, we need to measure the relationship between the
variables using covariance and correlation methods.