Information from the survey was stored electronically in the form of data items. In some cases, items were formed directly from individual survey questions while in others, items were derived from answers to several questions (e.g. Body Mass Index derived from measured height and weight). Some items were derived with reference to information from other organisations such as the National Health and Medical Research Council (e.g. in relation to guidelines on consumption of alcohol).
Datasets from the 2014-15 NHS are hierarchical in nature. A hierarchical data file is an efficient means of storing and retrieving information which describes one to many, or many to many, relationships; e.g. a person may report multiple days on which alcohol was consumed and also multiple types of alcoholic beverages on each of these days.
The structure of the 2014-15 NHS dataset is as follows:
- Household level - containing information about household size and structure, dwelling characteristics (including geographic classifications), and household income details.
- All Persons in Household level - containing basic demographic and relationship information about all members of households, including those members selected in the survey.
- Selected Person level - which is the main level, containing all demographic and socio-economic characteristics of survey respondents, and most of the health and related information they provided.
- Actions for priority, targeted conditions level - which is the main level for actions taken for priority, targeted health conditions (i.e. heart and circulatory conditions, diabetes mellitus, asthma, cancer, arthritis, osteoporosis and mental health) and contains information about actions taken by respondents in relation to their health conditions.
- Condition level - containing detailed information about the health conditions reported by respondents.
- Medications level - containing information about the types of medications and supplements used by respondents.
- Alcohol - Day Consumed level - containing information on alcohol consumption on the three most recent days on which respondents reported consuming alcohol, and the order of consumption.
- Alcohol - Type Consumed level - containing information on the order of consumption and the broad alcohol types and quantities for each type consumed on those days.
Data about households and families are contained as individual characteristics on person records. The questionnaire, data items and related output categories for this topic are available in pdf/ Excel spreadsheet format from the Downloads
page of this product.