HOW PRICE-TREND GRAPHS ARE CONSTRUCTED

1. The source of the data is the U.S. Energy Information Agency, EIA-826 Sales and Revenue Spreadsheets.
2. Prices shown are for average total delivered retail price (including energy, transmission, and distribution) over the twelve months ending with the month shown on the graph. For example, the prices may reflect the twelve months ending each February, with the most recent twelve-month period ending in February 2007.
3. This rolling twelve-month average is used because it captures prices over all seasons. However, a rolling twelve-month average also mutes sharp increases or decreases in a given month (e.g., January and February 2007) because those prices are averaged-in with previous months.
4. The “regulated states” include all states except CA, CT, DC, DE, MA, MD, ME, MI, NH, NJ, NY, RI, TX, which comprise the “deregulated” states. Characterizing a state as “regulated” or “deregulated” involves some judgment, since different states can have different approaches to pricing for different classes of customers and to divestiture of regulatory assets. In general, states whose residential customers retained regulated rates are defined as “regulated.” The states of IL, OH, PA, VA are included in regulated states, due to price caps in those states through 12/06. Price caps in Illinois were removed as of January 2007, but since the prices shown are for a twelve-month rolling average, Illinois will be reflected as “regulated” until more than six months are “deregulated” (no price caps). California suspended deregulation but remains in the “deregulated” category because significant regulatory assets were divested, some customers remain unregulated, and others are exposed to wholesale market rates due to divestiture. Montana is included in “regulated” states because it never fully exposed its residential customers to the open market, though its main utility did divest itself of its regulatory assets. Arguably, Montana should be included in the “deregulated” category, at least for a period of years, but doing so would not significantly change the graphs, because it is a small-population state. New Hampshire, another small state, is characterized as “deregulated,” even though some regulatory assets were preserved. Also, a "deregulated" state may include territories, notably those of public-power utilities, that have been exempted from the state's deregulation requirements. These graphs include all prices for all customers in a state, regardless of which utility or supplier serves them. The label "deregulated" or "regulated" is applied at the state level. Finally, prices for any given state are shown in either the "regulated" or "deregulated" line for the entire period, even though most states began deregulation around 1999 or 2000; prior to that time all states would have been classifed as "regulated." If you would like to see a different grouping of states, contact marilynDOTshowalterATppinetDOTorg.
5. Calculations and graphs were constructed in Excel and then uploaded in gif form. Individual graphs can be refined in appearance through other programs.
   
6. If you have requests or comments on these graphs, feel free to contact marilynDOTshowalterATppinetDOTorg.