limited, since there is an urgent need for current information. The study, which began in October 1972, took 24 months to complete, including writing this book. The energy crisis of 1973-74, which intervened, brought serious consumer shortages and sharply rising prices. This made clear the extent to which public policy then in the making would affect the public and the need for the facts we were assembling. Many of the facts come from two surveys. One was a national sample survey of households to find out about energy using characteristics of the households themselves and of their dwellings. The other survey was of the households' electricity and natural gas companies, made after receiving each household's consent. The utilities provided the actual amount and cost of the electricity and natural gas their customers used in the most recent twelve-month period. The two sets of information (from households and their utilities directly) made it possible to match the exact amount and cost of electricity and natural gas used with each household's characteristics and the characteristics of their homes. Answers on the household questionnaire gave the basis for making similar—but less accurate—estimates of gasoline use.

To analyze these data and add to general understanding of how energy use affects households, our research extended into a number of other areas, with primary focus on the cost of energy and the relationship of cost to households' means. We wanted to put numbers on the variations in energy use and cost among households of differing income and other characteristics. We also wanted to know how much households of all kinds depend on cars and gasoline for their transportation. We hoped to discover the main influences on household energy use. Of special interest also was the degree to which the fallout from energy use, in the form of air pollution, affects households of varying characteristics.

Wherever possible, we compared income groups, especially the poor with better-off households. The poor received special attention since we