Notes: The data in this graph are for households that used natural gas.
The percentiles describe the distribution of household natural gas consumption data; for example, 25% of households in units constructed before 1940 consumed less than 51 thousand cubic feet and 75% consumed more than that amount.
Source: 1997 Residential Energy Consumption Survey.

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Figure 2. Mean Annual Natural Gas Consumption (and 95% confidence ranges) by Year Constructed, 1997
(thousand cubic feet per household)

Notes: The data in this graph are for households that used natural gas.
The standard error is a measure of sampling error and can be used to calculate a confidence range. For example, the estimate for natural gas consumption in units constructed before 1940 is 103 thousand cubic feet (cf) and the standard error is 3 thousand cf. The 95% confidence interval is calculated by multiplying 1.96 times the standard error, and the 95% confidence range is 97 thousand cf to 109 thousand cf.
Source: 1997 Residential Energy Consumption Survey.

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