4324.0.55.001 - Microdata: National Health Survey, 2017-18  
Latest ISSUE Released at 11:30 AM (CANBERRA TIME) 30/04/2019   
   Page tools: Print Print Page Print all pages in this productPrint All

USING THE BASIC CURF

ABOUT THE BASIC CURF

The NHS 2017–18 Basic CURF contains unit records relating to all of the survey respondents. The data are released under the Census and Statistics Act 1905, which has provision for the release of data in the form of unit records where the information is not likely to enable the identification of a particular person or organisation. Accordingly, there are no names or addresses of survey respondents on the CURF and other steps, including the following list of actions, have been taken to protect the confidentiality of respondents:

  • the level of detail of many data items has been reduced by grouping, ranging or top coding values
  • some unusual records have been changed to protect against identification
  • excluding some data items that were collected

The nature of the changes made, and the relatively small number of records involved, ensure that the effects on data for analysis purposes is considered negligible. These changes also mean that estimates produced from the Basic CURF may differ from those published in National Health Survey: First Results, 2017-18 (cat. no. 4364.0.55.001), subsequent publications and the TableBuilder.


ACCESSING BASIC CURFS


Approved users can access basic CURFs via the MicrodataDownload page. To apply for access to the Basic CURF, follow the instructions via the Microdata Entry Page.


COUNTS AND WEIGHTS



NUMBER OF RECORDS BY LEVEL, NHS 2017-18 BASIC CURF

LEVELSRECORD COUNTS (UNWEIGHTED)
WEIGHTED COUNTS (if applicable)
Household level16 376
9 268 534
Person level (Selected persons)21 315
24 103 016
Alcohol Day27 848
N/A
Alcohol Type30 343
N/A
Conditions level87 107
N/A
Medication level52 901
N/A
Health Literacy level5 790
18 655 100



Weights and Hierarchical Files

Weight Variables

There are three weight variables on the file:

Household Weight (NHSFHHWT)
- Household level - Benchmarked
Person Weight (NHIFINWT)
- Selected Person level - Benchmarked to the total population.
Health Literacy Person Weight (HLSFINWT) - Health Literacy level - Benchmarked to the total population 18 years and over.

There is no weight associated with the other levels. This is because the records are repeated for each person. If, for example, NHSFINWT is merged onto the Conditions level, it will be attached to each condition record and therefore be repeated for each person where they have more than one condition. This should be considered when producing tables. See 'Copying information across levels' below for more information.

For more information about weights, see 'Reliability of Estimates' below.

Using Weights

The NHS is a sample survey, so to produce estimates for the in-scope population you must use weight fields in your calculations. When analysing a Household level item at the household level, you will need to use the household weight. For example, if you wanted to know the number of households in a state, rather than the number of persons living in that state.

Caution should be used when applying the ‘Household’ weight to items from other levels. For example, if the household weight is applied to a selected person level demographic item, such as ‘Sex’, your table will show the number of households with one or more selected persons of that sex. Since up to two people can be selected in the NHS, this will result in some households being counted twice, once for females and once for males.
Level of Data ItemEstimates if use Household WeightEstimates if use Person WeightEstimates if use with Health Literacy person weight

Household levelHouseholds with the specified characteristics.Persons in households with the specified characteristics.Not applicable for use on this level
Person level (Selected persons)Households containing one or more selected persons with the specified characteristics.Persons with the specified characteristics.Not applicable for use on this level
Alcohol DayHouseholds containing one or more selected persons with one or more alcohol days with the specified characteristics.Persons with one or more alcohol days with the specified characteristics.Not applicable for use on this level
Alcohol TypeHouseholds containing one or more selected persons with one or more alcohol types with the specified characteristics.Persons with one or more alcohol types with the specified characteristics.Not applicable for use on this level
Conditions levelHouseholds containing one or more selected persons with one or more conditions with the specified characteristics.Persons with one or more conditions with the specified characteristics.Not applicable for use on this level
Medication levelHouseholds containing one or more selected persons with one or more medications with the specified characteristics.Persons with one or more medications with the specified characteristics.Not applicable for use on this level
Health Literacy levelNot applicable for use on this levelNot applicable for use on this levelPersons, 18 years and over with specified Health Literacy characteristic



IDENTIFIERS


Every record on each level of the file is uniquely identified.

The identifiers ABSHIDB, ABSPID, ABSDID, ABSTID, ABSCID, ABSMID and ABSHID appear on all levels of the file. Where the information for the identifier is not relevant for a level, it has a value of 0. See the Data Item List for details on which ID equates to which level.

Each household has a unique thirteen digit random identifier, ABSHIDB. This identifier appears on the household level and is repeated on each level on each record pertaining to that household. The combination of identifiers uniquely identifies a record at a particular level as shown below.

1. Household = ABSHIDB
2. Person = ABSHIDB + ABSPID
3. Alcohol Day = ABSHIDB + ABSPID + ABSDID
4. Alcohol Type = ABSHIDB + ABSPID + ABSDID + ABSTID
5. Conditions = ABSHIDB + ABSPID + ABSCID
6. Medication = ABSHIDB + ABSPID + ABSMID
7. Health Literacy = ABSHIDB + ABSPID + ABSHID

The Household record identifier, ABSHIDB, assists with linking people from the same household, and also with household characteristics such as geography (located on the household level) to the Person records. When merging data with a level above, only those identifiers relevant to the level above are required.

Copying information across levels


The following SAS code is an example of copying information from a lower level to a level above:

PROC
SORT DATA=NHS17B.NHS17CNB OUT=SORTED_COB; /* Create a sorted temporary dataset based on the Conditions level */
BY ABSHIDB ABSPID ABSCID;

DATA
TOT_LTC (KEEP=ABSHIDB ABSPID ABSCID LONGTERM); /* Create a count of diagnosed, long-term conditions */
SET SORTED_COB;
BY ABSHIDB ABSPID; /* This step will go through each Condition record within each unique combination of ABSHIDB, ABSPID */
RETAIN LONGTERM;

IF FIRST.ABSPID THEN
DO;
LONGTERM=0;
END;

IF CONDSTAT=1 THEN LONGTERM=LONGTERM+1; /* Starts a count of the number of diagnosed, long-term conditions */

IF LAST.ABSPID THEN OUTPUT; /* This outputs the last record including the totals found for each unique combination of ABSHIDB and ABSPID */

PROC
SORT DATA=NHS17B.NHS17SPB OUT=SORTED_SPB; /* Create a sorted temporary dataset based on the Selected persons level */
BY ABSHIDB ABSPID;

DATA
MRGFILES;
MERGE TOT_LTC SORTED_SPB;
BY ABSHIDB ABSPID;

PROC
FREQ DATA=MRGFILES; /* This procedure gives a sample count of the data copied up from the Condition level to the Selected persons level */
TABLES LONGTERM /NOROW NOCOL NOCUM NOPERCENT;

RUN
;

The new variable LONGTERM gives a count of the number of diagnosed, long-term conditions per selected person on the Selected persons level. This new item can then be analysed with any other item on the Selected persons level.


The following SAS code is an example of copying information from a higher level to a level below:

PROC
SORT DATA=NHS17B.NHS17SPB OUT=SORTED_SPB (KEEP=ABSHIDB ABSPID AGEB SEX);
      BY ABSHIDB ABSPID;

      PROC
      SORT DATA=NHS17B.NHS17MDB OUT=SORTED_MDB;
      BY ABSHIDB ABSPID ABSMID;

      DATA
      MRGFILES;
      MERGE SORTED_MDB SORTED_SPB;
      BY ABSHIDB ABSPID;

      RUN
      ;

This merge matches one Person record to many Medications records. The data items copied from the person level ('AGEB' and 'SEX' in the example) will be repeated for the counting unit of the level they have been added to, Medications in this case. Each Medications record will therefore receive the same AGEB and SEX of the Person they belong to.


MULTI-RESPONSE ITEMS


A number of questions in the survey allowed respondents to provide one or more responses. Each response category for these multi-response data items is treated as a separate data item. On the CURF, these data items share the same identifier (SAS name) prefix but are each separately suffixed with a letter - A for the first response, B for the second response, C for the third response and so on.

For example, the multi-response data item 'Disability type' has six response categories (excluding 'Not applicable'). There are six data items named DISABA, DISABB, DISABC...DISABF. Each data item in the series will have either a positive response code or a null response code, with the exception of the first item in the series, DISABA. DISABA has three potential response codes: the positive response code 1 - 'Sight, hearing, speech', the code 0 - null response, as well as the additional response code, code 7 - 'Not applicable'. The remaining items DISAB--F have just the two response codes each. The data item list identifies all multi-response items and lists the corresponding codes with the corresponding response categories.

Note that the sum of individual multi-response categories will be greater than the population applicable to the particular data item as respondents are able to select more than one response.


RELIABILITY OF ESTIMATES


As the survey was conducted on a sample of private households in Australia, it is important to take account of the method of sample selection when deriving estimates from the CURF. This is particularly important as a person's chance of selection in the survey varied depending on the state or territory in which the person lived. If these chances of selection are not accounted for by use of appropriate weights, the results will be biased. For details on the NHS weighting process, see Weighting, Benchmarking and Estimation in National Health Survey: First Results, 2017-18 - Explanatory Notes (cat. no. 4364.0.55.001).

Each person record has a main weight (NHIFINWT). This weight indicates how many population units are represented by the sample units. When producing estimates of sub-populations from the CURF, it is essential that they are calculated by adding the weights of persons in each category and not just by counting the sample number in each category. If each person's weight were to be ignored when analysing the data to draw inferences about the population, then no account would be taken of a person's chance of selection or of different response rates across population groups, with the result that the estimates produced could be biased. The application of weights ensures that estimates will conform to an independently estimated distribution of the population by age, by sex, etc. rather than to the distributions within the sample itself.

Each person record on the CURF contains 60 replicate weights in addition to the main weight. Replicate weights can be used to calculate measures of sampling error. For details on sampling error calculations and replicate weights, see Technical Note.


BASIC CURF FILES

ASCII text format files

These files contain the raw confidentialised survey data in comma delimited ASCII text format.

NHS17HHB.csv contains Household level data
NHS17SPB.csv contains Person level data
NHS17A3B.csv contains Alcohol day level data
NHS17A4B.csv contains Alcohol type level data
NHS17CNB.csv contains Conditions level data
NHS17MDB.csv contains Medications level data
NHS17HLB.csv contains Health Literacy level data

SAS files

These files contain the data for the CURF in SAS format.

NHS17HHB.sas7bdat contains Household level data
NHS17SPB.sas7bdat contains Person level data
NHS17A3B.sas7bdat contains Alcohol day level data
NHS17A4B.sas7bdat contains Alcohol type level data
NHS17CNB.sas7bdat contains Conditions level data
NHS17MDB.sas7bdat contains Medications level data
NHS17HLB.sas7bdat contains Health Literacy level data

SPSS files

These files contain the data for the CURF in SPSS format.

NHS17HHB.sav contains Household level data
NHS17SPB.sav contains Person level data
NHS17A3B.sav contains Alcohol day level data
NHS17A4B.sav contains Alcohol type level data
NHS17CNB.sav contains Conditions level data
NHS17MDB.sav contains Medications level data
NHS17HLB.sav contains Actions level data

STATA files

These files contain the data for the CURF in STATA format.

NHS17HHB.dta contains Household level data
NHS17SPB.dta contains Person level data
NHS17A3B.dta contains Alcohol day level data
NHS17A4B.dta contains Alcohol type level data
NHS17CNB.dta contains Conditions level data
NHS17MDB.dta contains Medications level data
NHS17HLB.dta contains Actions level data

Information files

FORMATS.sas7bcat is a SAS library containing formats

NHS17HHB.sas contains a SAS program to load NHS17HHB.csv and the SAS formats into SAS for Windows
NHS17SPB.sas contains a SAS program to load NHS17SPB.csv and the SAS formats into SAS for Windows
NHS17A3B.sas contains a SAS program to load NHS17A3B.csv and the SAS formats into SAS for Windows
NHS17A4B.sas contains a SAS program to load NHS17A4B.csv and the SAS formats into SAS for Windows
NHS17CNB.sas contains a SAS program to load NHS17CNB.csv and the SAS formats into SAS for Windows
NHS17MDB.sas contains a SAS program to load NHS17MDB.csv and the SAS formats into SAS for Windows
NHS17HLB.sas contains a SAS program to load NHS17HLB.csv and the SAS formats into SAS for Windows

IMPORTANT INFORMATION.pdf describes the file contents of the CURF and information on using the CURF
COPYRITE1.bat describes Copyright obligations for CURF users

Frequency files

The following plain text format files contain data item code values and category labels at each level, with frequencies for each value.

FREQUENCIES_NHS17HHB.txt contains Household level data
FREQUENCIES_NHS17SPB.txt contains Person level data
FREQUENCIES_NHS17A4B.txt contains Alcohol day level data
FREQUENCIES_NHS17A4B.txt contains Alcohol type level data
FREQUENCIES_NHS17CNB.txt contains Conditions level data
FREQUENCIES_NHS17MDB.txt contains Medications level data
FREQUENCIES_NHS17HLB.txt contains Health Literacy level data


Back to top of the page