perception of its "permanent" or future income (in a broad sense) was introduced by Milton Friedman in his famous Theory of the Consumption Function, and has been studied, debated, and elaborated upon ever since. Unfortunately in spite of attention economists have given to this concept, little has been done to incorporate its essential good sense into analyzing consumer behavior. Most studies about consumers, including this one, have used instead the much easier dimension of reported income. Here is a research challenge of substantial import—to assess the influence of economic security and the household's perception of its permanent and future income on energy consumption.

We began our work by saying it was about "life styles and energy." With great disappointment, we came to the conclusion quite early that we had neither the flexibility nor the time to develop a theoretical framework for relating an essentially qualitative phenomenon (life style) to one that, while partly qualitative, could still be quantified (energy use). To sociologists who wish to work quantitatively, life style has been a troublesome concept. We were optimistic that some of the criteria in the household questionnaire would help us, but the strictures of our study—budget, survey sample, time frame, questionnaire length, and requirements for developing energy estimates—proved too formidable. With particular emphasis on life style, we might have fruitfully followed the work of Susan Ferge and others who have collected and analyzed data on how individuals spend their time. We refer readers especially to The Use of Time, a fascinating book about the daily activities of urban and suburban populations in twelve countries.

In analyzing social stratification in Hungary, Susan Ferge found she could demonstrate "the evolution of `quantitative' and `qualitative' differentiation: the gradual fading away of basic, quantitative differences and the growing importance of more subtle, qualitative ones." She discovered more variety and enrichment in every component of the way of life with improved material conditions. These tendencies were accompanied by a search for conspicuous behavior that gave objects as well as attitudes a symbolic value that served to represent social standing.

Surely for Americans, the kind of house and car and their accessories—not to mention their number and, in the case of the house, its location—fits into this scheme. This has great relevance for energy use, but we must leave to others its deeper study.