* The End User License file (EULF) dataset is a sample of just over 4 million households
* EULF is a semi-random sample of the 8m records which have an Energy Performance Certificate.
* It includes only those with valid values on key variables (Property Age, Property Type, Floor Area Band and Energy Efficiency Band) and (especially) valid observations for electricity in 2012.
* Records were selected based on the frequency of household type in the dataset relative to the total dwelling stock so that uncommon property types are over-represented, common types are under-represented and the supplied weight corrects for this.
* Records were selected based on the frequency of household type in the dataset relative to the total dwelling stock so that uncommon property types (e.g. older detached properties) are over-represented and common types (e.g. flats where turnover is high) are under-represented. The supplied weight corrects for this for descriptive analaysis.
* Implications for sample bias unclear - there may be other systematic biases not captured by the weight?
* Bias caused by linkage failure is unknown although the DECC NEED Data Framework report from 2011 suggest match rates of 94%-100% (https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/209264/Annex_B_-_Quality_Assurance.pdf)
