4324.0.55.001 - Microdata: National Health Survey, 2014-15 Quality Declaration 
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This document was added 04/10/2014.



USING THE BASIC CURF


ABOUT THE BASIC CURF

The NHS 2014–15 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
    • income data has been perturbed.

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, 2014-15 (cat. no. 4364.0.55.001), subsequent publications and the TableBuilder.


ACCESSING BASIC CURFS

Approved users can access basic CURFs in their own environment (via a CD-ROM), as well as via the Remote Access Data Laboratory (RADL) and DataLab. 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 2014-15 BASIC CURF

LEVELSRECORD COUNTS (UNWEIGHTED)
WEIGHTED COUNTS (if applicable)
Household level14 726
8 843 327
Person level (Selected persons)19 257
22 966 642
Alcohol Day25 230
N/A
Alcohol Type27 821
N/A
Actions (Condition Group)25 568
N/A
Conditions level76 043
N/A
Medication level47 423
N/A


Weights and Hierarchical Files

Weight Variables

There are two weight variables on the file:

Household Weight (NHSFHHWT)
- Household level - Benchmarked
Person Weight (NHSFINWT)
- Selected Person level - Benchmarked to the total population.

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 Weight
Household levelHouseholds with the specified characteristics.Persons in households with the specified characteristics.
Person level (Selected persons)Households containing one or more selected persons with the specified characteristics.Persons with the specified characteristics.
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.
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.
Actions (Condition Group)Households containing one or more selected persons with one or more actions with the specified characteristics.Persons with one or more actions with the specified characteristics.
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.
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.



IDENTIFIERS

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

The identifiers ABSHIDB, ABSPID, ABSDID, ABSTID, ABSGID, ABSCID AND ABSMID 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. Actions = ABSHIDB + ABSPID + ABSGID
6. Conditions = ABSHIDB + ABSPID + ABSCID
7. Medication = ABSHIDB + ABSPID + ABSMID

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=NHS14B.NHS14COB 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=NHS14B.NHS14SPB 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=NHS14B.NHS14SPB OUT=SORTED_SPB (KEEP=ABSHIDB ABSPID AGEB SEX);
    BY ABSHIDB ABSPID;

    PROC SORT DATA=NHS14B.NHS14ATB OUT=SORTED_ATB;
    BY ABSHIDB ABSPID;

    DATA MRGFILES;
    MERGE SORTED_ATB SORTED_SPB;
    BY ABSHIDB ABSPID;

    RUN;

This merge matches one Person record to many Actions 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, Actions in this case. Each Actions 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, 2014-15 - Explanatory Notes (cat. no. 4364.0.55.001).

Each person record has a main weight (NHSFINWT). 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.

NHS14HHB.csv contains Household level data
NHS14SPB.csv contains Person level data
NHS14ALB.csv contains Alcohol day level data
NHS14ATB.csv contains Alcohol type level data
NHS14ACB.csv contains Actions level data
NHS14COB.csv contains Conditions level data
NHS14MDB.csv contains Medications level data

SAS files

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

NHS14HHB.sas7bdat contains Household level data
NHS14SPB.sas7bdat contains Person level data
NHS14ALB.sas7bdat contains Alcohol day level data
NHS14ATB.sas7bdat contains Alcohol type level data
NHS14ACB.sas7bdat contains Actions level data
NHS14COB.sas7bdat contains Conditions level data
NHS14MDB.sas7bdat contains Medications level data

SPSS files

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

NHS14HHB.sav contains Household level data
NHS14SPB.sav contains Person level data
NHS14ALB.sav contains Alcohol day level data
NHS14ATB.sav contains Alcohol type level data
NHS14ACB.sav contains Actions level data
NHS14COB.sav contains Conditions level data
NHS14MDB.sav contains Medications level data

STATA files

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

NHS14HHB.dta contains Household level data
NHS14SPB.dta contains Person level data
NHS14ALB.dta contains Alcohol day level data
NHS14ATB.dta contains Alcohol type level data
NHS14ACB.dta contains Actions level data
NHS14COB.dta contains Conditions level data
NHS14MDB.dta contains Medications level data

Information files
FORMATS.sas7bcat is a SAS library containing formats

NHS14CHHB.sas contains a SAS program to load NHS14BCHHD.csv and the SAS formats into SAS for Windows
NHS14CSPB.sas contains a SAS program to load NHS14BCSPS.csv and the SAS formats into SAS for Windows
NHS14CALCB.sas contains a SAS program to load NHS14BCALC.csv and the SAS formats into SAS for Windows
NHS14CALTB.sas contains a SAS program to load NHS14BCALT.csv and the SAS formats into SAS for Windows
NHS14CACTB.sas contains a SAS program to load NHS14BCACT.csv and the SAS formats into SAS for Windows
NHS14CCONB.sas contains a SAS program to load NHS14BCCON.csv and the SAS formats into SAS for Windows
NHS14CMEDB.sas contains a SAS program to load NHS14BCMED.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_NHS14HHB.txt contains Household level data
FREQUENCIES_NHS14SPB.txt contains Person level data
FREQUENCIES_NHS14ALB.txt contains Alcohol day level data
FREQUENCIES_NHS14ATB.txt contains Alcohol type level data
FREQUENCIES_NHS14ACB.txt contains Actions level data
FREQUENCIES_NHS14COB.txt contains Conditions level data
FREQUENCIES_NHS14MDB.txt contains Medications level data