| MAISY RECS Hourly Loads & Emissions Databases |
Question 9. Can I Use MAISY RECS Data for Residential Household Segment Analysis?
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Short Answer: Yes. This answer is similar to the answer to question 8.
Make sure that household segments include enough households within individual segments
to provide a representative sample. The number of households in each segment
should be no smaller than about 20 households. See the longer answer below for suggestions
on how to evaluate the reliability of household segments.
Longer Answer: The Residential Energy Consumption Survey (RECS) sample was designed to provide a statistically representative sample of all households in each state. RECS sample design takes into account demographic, income and other diversity that exists in each state. We recommend that household segments include at least 20 households for individual segment variables of interest. However, it is important to remember that RECS databases are surveys so any results that are calculated from database variables include some sampling error as is the case with any survey database. Calculating variable averages, say average lighting/TV kWh use, from the RECS database will include a +/- margin of error as is the case with any survey database. Calculating variable averages from smaller segment samples can result in unacceptably large sampling errors. One way to judge the extent to which smaller samples are contributing to larger sampling errors is to calculate the variable average for different total sample sizes. For example if an individual segment average reflecting a sample of 20 households is significantly different than one calculated with a sample of 30 households, but a sample of 40 households provides an estimate similar to that of the 30 household sample, one can infer that the 20 household sample in not representative of the population and the variable average should be based on that provided by the 30 household sample. While MAISY RECS Databases support general drill-downs such as segmenting 7 am household space heating peak kW by dwelling unit floor space, multiple segmentation including 5 floor space categories and 5 income categories may provide segments with too few households in each segment to be reliable estimates. As an alternative to applying MAISY RECS Databases for detailed customer segments with limited sample households, consider standard MAISY Residential Energy Use and Hourly Loads Databases that provide a sample of 6.7 million residential households across the US rather than the 18,400+ households in the MAISY RECS Databases. Standard MAISY Residential Energy Use and Hourly Loads Databases also provide ZIP-level geographic detail compared to the RECS state level detail. The RECS state samples are not designed to provide statistical accuracy for multiple drilldowns. For example, a drill down to find load profiles of households with electric space heating and dwelling units greater than 3000 square feet may provide fewer than 20 records. We recommend that drilldowns include 20 or more records to reflect reliable average results. An analysis of the households in this small sample is also recommended to ensure that one or more individual record results are not extreme and unduly influencing the average results. |
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