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Background Notes

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Purpose of Survey

The Irish Health Survey (IHS) was collected under Regulation (EC) No 1338/2008 of the European Parliament and of the Council of 16 December 2008 on Community statistics on public health and health and safety at work1. This survey fulfils the need for public health policies to obtain reliable data on health status, health care usage and health determinants.

The Central Statistics Office wishes to thank the participating households for their co-operation in agreeing to take part in the survey, and for facilitating the collection of the relevant data. 


The Irish Health Survey was designed in line with the third wave of the European Health Interview Survey (EHIS)2.  The collection of the data under the aforementioned European Regulation implies that harmonised data can be obtained across the European continent.

The Irish Health Survey can be divided into three fundamental components.  These are the European Health Status Module (EHSM), the European Health Care Module (EHCM), and the European Health Determinants Module (EHDM).

The European Health Status Module:

The module on health status is a central element of the survey. It allows measurement of the health status of the population in general, and not only in relation to specific health problems. It covers different aspects and dimensions of health: physical and mental health, chronic and temporary problems and specific conditions. It covers the general impact on the functional status and the limitations in activities of daily living of the respondents.  The first three general questions on self-perceived health, long standing illnesses or health problems, and activity limitations constitute the Minimum European Health Module (MEHM).

The European Health Care Module:

The ECHM module collects data on the use of health care services and the unmet needs for health care. Information on health care consumption is an essential part of the health information system in order to assign necessary resources to the population. This allows analysis of the relationships between health consumption and several determinants such as health status, lifestyles or socio-demographic characteristics as well as the relationships between different types of health care use.

The European Health Determinants Module: 

The general focus of this module is to measure aspects in lifestyles or health-related behaviours. These may have a positive or negative impact on an individual’s health status.

Along with the above data, additional variables collected included were; NUTS3 region, sex, age, nationality, and level of deprivation. A copy of the Irish Health Survey questionnaire is available here: IHS Questionnaire

Sample Design

The sample was derived for the General Household Survey (GHS)3. It is a multi-stage cluster sample resulting in all households in Ireland having an equal probability of selection. The sample is stratified using administrative county and the Pobal HP (Haase and Pratschke) Deprivation Index (quintile).

A two-stage sample design is used. Firstly, 1,200 blocks are selected using Probability Proportional to Size (PPS) sampling. All occupied households on Census night 2016 within each block were eligible for selection in the Social Statistics Sample.

Secondly, households within blocks were selected using simple random sampling (SRS) without replacement for inclusion in the survey sample. This ensures each household in the sample frame has an equal probability of selection.

The sample size is based on a simple random sampling approach and before design effects are factored in, this was determined by Eurostat as 5,125 for Ireland. Adjusting this figure for the design effect (to account for how the sampling is actually conducted in practice) means that a higher achieved sample is required – thus the approximately 7,600 responses actually collected by this survey.

Data Collection

Once the second stage of the sampling procedure is complete, a single individual is randomly selected from each household.  This individual must be aged 15 years or older. Once the individual is selected, their responses are collected face-to-face (CAPI) via a tablet. Proxies were not allowed for data collection.

It is worth noting the data for the previous Irish Health Survey 2015 (Irish Health Survey 2015) was collected via paper survey form (PAPI). This paper survey form was completed by the respondent and returned by post. 

There were 7,621 respondents to this survey in 2019. The reference period for the survey is 2019. Data collection began in Q2 2019 and, to achieve a sufficient number of responses, data collection finished in Q1 2020 (as agreed with Eurostat).

Grossing/derivation of results

The GHS grossing procedure aligns the distribution of persons covered in the sample with independently determined population estimates at the level of sex, five-year age group and region. The grossed population aged 15 years or older is 3,925,556 persons.

To provide national population results, the survey results were weighted to represent the entire population (15+). The survey results were weighted to agree with population estimates broken down by age group, sex, ISCED11 and region.

Household weights were calculated for all households in the initial sample. The design weights are computed as the inverse of the selection probability of the unit. The purpose of design weights is to eliminate the bias induced by unequal selection probabilities.

These design weights were then adjusted for non-response. This eliminated the bias introduced by discrepancies caused by non-response, particularly critical when the non-responding households are different from the responding ones in respect to some survey variables as this may create substantial bias in the estimates. Design weights are adjusted for non-response by dividing the design weights of each responding unit in the final/achieved sample by the (weighted) response probability of the corresponding group or strata.

To obtain the final household weights for the results, after the previous steps were carried out, the distribution of households by deprivation, NUTS3 region, sex and age was calibrated to the population of households in Quarter 1 2018 (as derived from the LFS Survey). The CALMAR2-macro, developed by INSEE, was used for this purpose. 


The regional classifications in this release are based on the NUTS (Nomenclature of Territorial Units) classification used by Eurostat. Until Q4 2017, the NUTS3 regions corresponded to the eight Regional Authorities established under the Local Government Act, 1991 (Regional Authorities) (Establishment) Order, 1993, which came into operation on 1 January 1994 while the NUTS2 regions, which were proposed by Government and agreed by Eurostat in 1999, were groupings of those historic NUTS3 regions.

However, the NUTS3 boundaries were amended on 21st of November 2016 under Regulation (EC) No. 2066/2016 and have come into force from Q1 2018. These new groupings are reflected in the CSO publications from Q1 2018 onwards. The changes resulting from the amendment are that County Louth has moved from the Border to the Mid-East and what was formerly South Tipperary has moved from the South-East to the Mid-West, resulting in the new NUTS2 and NUTS3 regions: 

Northern & Western
NUTS2 Region
NUTS2 Region
Eastern & Midland
NUTS2 Region
Border Cavan Mid-West Clare Dublin Dublin City
  Donegal   Limerick City & County    Dun Laoghaire-Rathdown
  Leitrim   Tipperary    Fingal
  Monaghan       South Dublin 
  Sligo South-East Carlow    
      Kilkenny  Mid-East Kildare
West Galway City    Waterford City & County   Meath
  Galway County   Wexford    Wicklow
  Mayo       Louth
  Roscommon  South-West Cork City    
      Cork County Midland Laois
      Kerry    Longford

Deprivation Index

The Pobal Haase-Pratschke Deprivation Index is used to create the underlying sample and is used to analyse the data. The Index uses Census data to measure levels of disadvantage or affluence in a geographical area. More detailed information on the index can be found on the Trutz-Haase website.

The results are presented by quintiles, five equal-sized groups of households, with the first quintile representing the most disadvantaged area and the fifth quintile representing the least deprived/most affluent area. The five quintiles are described below:

First Quintile - Very disadvantaged

Second Quintile - Disadvantaged

Third Quintile - Average

Fourth Quintile - Affluent

Fifth Quintile - Very affluent (least deprived).

Disclosure control

Estimates for number of persons where there are less than 30 persons in a cell are too small to be considered reliable. These estimates are presented with an asterisk (*) in the relevant tables.

Where there are 30-49 persons in a cell, estimates are considered to have a wider margin of error and should be treated with caution. These cells are presented with parentheses [ ].

In the case of rates, these limits apply to the denominator used in generating the rate. In the case of annual changes, both the current year and the preceding year are taken into account when deciding whether the estimate should be suppressed or flagged as having a wider margin of error. 

Diseases and Chronic Conditions

The full list of diseases and chronic conditions are as follows:

  • Asthma
  • Chronic bronchitis, chronic obstructive pulmonary disease or emphysema
  • A myocardial infarction (heart attack) or chronic consequences of myocardial infarction
  • Coronary heart disease or angina pectoris
  • High blood pressure
  • A stroke or the chronic consequence of a stroke (cerebral haemorrhage or cerebral thrombosis)
  • Arthrosis (excluding arthritis)
  • Lower back disorder or other chronic back defects
  • Neck disorder or other chronic neck defects
  • Diabetes (Type 1 or Type 2)
  • Allergy such as rhinitis, eye inflammation, dermatitis, food allergy or other (excluding allergic asthma)
  • Cirrhosis of the liver
  • Urinary incontinence, problems in controlling the bladder
  • Kidney problems
  • Depression
  • High blood lipids

Problems which are seasonal/ intermittent, or which are absent due to medical treatment are included.

Faecal Occult Blood Test Definition

The faecal occult blood test is a lab test used to check stool samples for hidden (occult) blood.  It can be used to help diagnose certain conditions including, but not limited to, gastric or duodenal ulcers, ulcerative colitis, bowel polyps, and bowel (colorectal) cancer. 

Mental Health Status Definition

The Personal Health Questionnaire (PHQ-8), 8-item depression screener, was selected as the instrument to monitor mental health and it encompasses a subset of the negative mental health dimension – mental health problems.  It is an instrument for assessing and monitoring the prevalence and severity of current depressive symptoms and functional impairment and to make tentative depression diagnosis.  It is originally derived from the Brief Health Questionnaire, Depression Module (PHQ-9).

Mental health status is calculated using data from question thirteen of the questionnaire.  In this question, there are eight items measuring various negative mental health effects experienced in the previous two weeks.  Each of these items has four possible answers:

  • None of the days
  • Several of the days
  • More than half of the days
  • Nearly every day

Each of these responses is then given a score; None of the days = 0, Several of the days = 1, More than half of the days = 2, and finally Nearly every day = 3.  The respondent’s scores for each of the eight items are then summed, giving a maximum of 24.  The levels of depression are identified by their final score, and the categories are as follows:

  • 0-4:        None to minimal depression
  • 5-9:        Mild depression
  • 10-14:    Moderate depression
  • 15-24:    Moderately severe or severe depression. 

Body Mass Index (BMI)

Body Mass Index (BMI) is a simple index of weight-for-height that is commonly used to classify underweight, overweight and obesity in adults. It is defined as the weight in kilograms divided by the square of the height in metres (kg/m2).

In the European Health Interview Survey, four BMI categories are present.  These are;

  • Underweight:                 Greater than 0 but less than 18.5
  • Normal Weight:              18.5 to 24.9
  • Overweight:                   25 to 29.9
  • Obese:                          Greater than or equal to 30.

Rates as calculated from the Irish Health Survey are not directly comparable with the Department of Health “Healthy Ireland” Survey rates, due to methodological differences between the two surveys[2], but they may provide some insight into general trends.

Binge Drinking

Binge drinking is defined by health experts, such as the World Health Organisation (WHO), as six or more standard drinks in one sitting, which is the equivalent of three or more pints of beer or six or more pub measures of spirits.

Regulation (EC) No 1338/2008

European Health Interview Survey (EHIS wave 3)

The General Household Survey (GHS) is a national survey that place takes place three or four times each year. The survey usually has a core of common demographic questions that are always asked (e.g. age, sex, education, etc.) plus one or more specific sets of survey questions that will change each year. You can find more information here:  General Household Survey.

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