4324.0.55.003 - Microdata: Australian Health Survey, Core Content - Risk Factors and Selected Health Conditions, 2011-12 Quality Declaration 
Latest ISSUE Released at 11:30 AM (CANBERRA TIME) 05/11/2014  First Issue
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USING THE EXPANDED CURF

ABOUT THE EXPANDED CURF
ACCESSING EXPANDED CURFS
COUNTING UNITS AND WEIGHTS
IDENTIFIERS
COPYING INFORMATION ACROSS LEVELS
RELIABILITY OF ESTIMATES
EXPANDED CURF FILES

ABOUT THE EXPANDED CURF

The Australian Health Survey, Core Content 2011-12 Expanded 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.

The changes mean that estimates produced from the CURF may differ from those published in released publications.

Detailed information about the data collected, comments regarding data quality and other points to assist in using and interpreting the data are contained in Australian Health Survey: Users' Guide, 2011-13 (cat. no. 4363.0.55.001). It is recommended that relevant parts of the guide be read in conjunction with the use of the AHS Core Content Expanded CURF.

ACCESSING EXPANDED CURFS

Expanded CURFs can only be accessed via the Remote Access Data Laboratory (RADL). Users must have applied for use of the RADL prior to using the Expanded CURF microdata. Details on the RADL can be found here - Remote Access Data Laboratory.

COUNTING UNITS AND WEIGHTS
NUMBER OF RECORDS BY LEVEL, AHS CORE CONTENT 2011-12 EXPANDED CURF

LEVELSCOUNTING UNITS
RECORD COUNTS
WEIGHTED COUNTS
Household levelHousehold
25 080
8 581 354
Persons in HouseholdAll persons in household (including selected persons)
61 657
N/A
Person levelSelected persons
31 837
21 526 456
Conditions levelConditions
42 037
N/A
Biomedical levelSelected persons (Biomedical participants - weighted)
31 837
20 649 321


Weights and Hierarchical Files

There are 3 weights associated with these files:

Household Weight PAA (AHSFHHWT) - Household level - Benchmarked to produce household estimates
Person Weight PAA (AHSPERWT) - Selected Person level - Benchmarked to produce population estimates for persons 2 years and over
Biomedical Weight PAA (NHMSPERW) - Biomedical level - Benchmarked to produce population estimates for person 5 years and over. Note that this level also contains non-biomedical participant records however their biomedical weight is set to 0 so they won't contribute to estimates. When using biomedical variables inconjunction with other variables on the biomedical level or with variables from other levels, the biomedical weight should be used.

There is no weight associated with the Persons in household level. This level is available in order to produce compositional information about the household (e.g. Number of persons in household aged 4-14 years) which can then either be used with the household weight to represent for example the the number of households with at least two persons aged 4-14 years, or with the person weight to represent the number of people living in household that contain at least two persons aged 4-14 years.

There is also no weight associated with the Conditions level. This is because the condition records are repeated for each person. If, for example, AHSPERWT 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.

Using Weights

The AHS is a sample survey. To produce estimates for the in-scope population you must use weight fields in your calculations.

LEVELSESTIMATES IF USE HOUSEHOLD WEIGHTSESTIMATES IF USE PERSON WEIGHTS
Household levelHouseholds with the specified characteristics.Persons with the specified household characteristics (based on selected person)
Persons in HouseholdHouseholds containing one or more persons with the specified characteristicsN/A (see above for details on using this level)
Person levelHouseholds containing one or more selected persons with the specified characteristicsPersons 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.
Biomedical levelHouseholds containing one or more selected biomedical persons with specified characteristics.Use Biomedical weight to calculate persons with specified characteristics.


Note that when applying the household weight to other levels, the weight will be multiplied by the number of people in the household on that level. If household estimates are desired, then the characteristic variables should be turned into a household variable. As mentioned previously, the desired population output for the conditions level should also be considered prior to applying the person weight.

For more information about weights see Reliability of Estimates below.

IDENTIFIERS

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

The identifiers ABSHHRID, ABSAPRID, ABSSPRID, ABSCNRID, ABSBIRID 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. Relevant identifiers for each level is as follows:
1. Household = ABSHHRID
2. Persons in household = ABSHHRID ABSAPRID
3. Person = ABSHHRID ABSAPRID ABSSPRID
4. Conditions = ABSHHRID ABSAPRID ABSSPRID ABSCNRID
5. Biomedical = ABSHHRID ABSAPRID ABSSPRID ABSBIRID

Each household has a unique thirteen digit random identifier, ABSHHRID. 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.

The combination of ABSHHRID ABSAPRID ABSSPRID ABSCNRID identifies each individual condition record a person has. When merging data with a level above, only those identifiers relevant to the level above are required. However, when merging for example the conditions level with the person level, the data on the person level will duplicate for each condition. See Copying information across levels below for more information.

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=AHS11ECN;
BY ABSHHRID ABSAPRID ABSSPRID;

DATA TTLLT (KEEP=ABSHHRID ABSAPRID ABSSPRID LONGTERM CURRNOT);
SET AHS11ECN;
BY ABSHHRID ABSAPRID ABSSPRID;

RETAIN LONGTERM NOTCURR;
IF FIRST.ABSSPRID THEN DO; LONGTERM=0; CURRNOT=0; END; /* Note as the file is sorted by the three IDs, reference to first is only needed for the last part of the ID */
IF AHSSTAT=1 THEN LONGTERM=LONGTERM+1; /*starts a count of the number of diagnosed long term conditions*/
IF AHSSTAT=3 THEN CURRNOT=CURRNUT+1; /*starts a count of the number of diagnosed conditions that are not current*/

IF LAST.ABSSPRID THEN OUTPUT;

PROC SORT DATA=AHS11ESP;
BY ABSHHRID ABSAPRID ABSSPRID;

DATA MRGFILES;
MERGE TTLLT AHS11ESP;
BY ABSHHRID ABSAPRID ABSSPRID;

PROC FREQ DATA=MRGFILES; /*This procedure gives a weighted count of the data copied up from the condition level*/
TABLES LONGTERM CURRNOT;
WEIGHT AHSPERWT;

RUN;

The new variables LONGTERM and CURRNOT produce the number of collected conditions a person has that are either diagnosed/longterm or diagnosed/not current. So they are meaningful on the person level, where only one value per record is produced for each variable. Merging the new variables onto the person level allows them to be analysed with any other items on the person level and for weighted estimates to be correctly produced.

The following SAS code is an example of copying information from a higher level to a level below:
DATA PERSON (KEEP=ABSHHRID ABSAPRID ABSSPRID AGEC SEX);
SET AHS11ESP;

PROC SORT DATA=PERSON;
BY ABSHHRID ABSAPRID ABSSPRID;

PROC SORT DATA=AHS11ECN;
BY ABSHHRID ABSAPRID ABSSPRID;

DATA MRGFILES
MERGE AHS11ECN PERSON;
BY ABSHHRID ABSAPRID ABSSPRID;

RUN;

This merge matches one person record to many conditions records. So, the data items copied from the person level ('AGEC' and 'SEX' in the example) will be repeated for the counting unit of the level they have been added to, conditions in this case.


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 weighting process see Weighting, Benchmarks and Estimation procedures in Australian Health Survey: Users' Guide, 2011-13 (cat. no. 4363.0.55.001).

Each person record has a main weight (AHSPERWT). 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 the Technical Note in the Australian Health Survey: Users' Guide, 2011-13 (cat. no. 4363.0.55.001).


EXPANDED CURF FILES

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

AHS11EHH.sas7bdat contains the Household level data
AHS11EAP.sas7bdat contains the Persons in Household level data
AHS11ESP.sas7bdat contains the Person level data
AHS11ECN.sas7bdat contains the Condition level data
AHS11EBI.sas7bdat contains the Biomedical level data

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

AHS11EHH.sav contains the Household level data
AHS11EAP.sav contains the Persons in Household level data
AHS11ESP.sav contains the Person level data
AHS11ECN.sav contains the Condition level data
AHS11EBI.sav contains the Biomedical level data


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

AHS11EHH.dta contains the Household level data
AHS11EAP.dta contains the Persons in Household level data
AHS11ESP.dta contains the Person level data
AHS11ECN.dta contains the Condition level data
AHS11EBI.dta contains the Biomedical level data

Information files

FORMATS.sas7bcat is a SAS library containing formats

Frequency files

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

ECURF AHS11E Household freqs.txt contains frequencies for Household level items
ECURF AHS11E Persons in Household freqs.txt contains frequencies for Persons in Household level items
ECURF AHS11E Person freqs.txt contains frequencies for Person level items
ECURF AHS11E Condition freqs.txt contains frequencies for Condition level items
ECURF AHS11E Weighted Biomedical freqs.txt contains the weighted frequencies for the Biomedical level items
ECURF AHS11E Unweighted Biomedical freqs.txt contains the unweighted frequencies for the Biomedical level items


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