4324.0.55.002 - Microdata: Australian Health Survey, Nutrition and Physical Activity, 2011-12 Quality Declaration 
Latest ISSUE Released at 11:30 AM (CANBERRA TIME) 18/12/2013  First Issue
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This document was added 11/06/2015.



USING TABLEBUILDER

Instructions on how to use TableBuilder can be found in the User Manual: TableBuilder (cat. no. 1406.0.55.005) and via the help links within the product itself.

For support in the use of TableBuilder and analysis of the data generated from TableBuilder, please contact Microdata Access Strategies on 02 6252 7714 or via microdata.access@abs.gov.au.

As discussed on the File Structure page of this product, this survey is hierarchical in nature. For the TableBuilder the following structure is in place:



Note on Continuous Items

Some continuous data items are allocated special codes for certain responses (e.g. 9999 = 'Not applicable'). When creating ranges for such continuous items for use in the TableBuilder, these special codes will NOT be included in these ranges (any special codes for continuous (summation) data items are listed in the Data Item List and will be found in the categorical version of the continuous item). However, note that labelling of 0s in the DIL does not necessarily mean they are excluded from the ranges (for example - identifying 0 as 'Did not visit' or 'Did not do') as they may still be important in some calculations. Reference should be made to the categorical version of the item to identify which codes are specifically excluded. Therefore the total shown only represents 'valid responses' of that continuous data item rather than all responses (including special codes).

For example:

Systolic Blood Pressure is located both in the Person level folder...



...and the Summation Options.



The following table shows the responses for 'Systolic Blood Pressure' by 'Sex of person'. The continuous values of the data item are contained in the 'A valid response was recorded' row. If the actual continuous values are to be displayed, then it is necessary to create a range for them. For information on constructing ranges see the User Manual: TableBuilder (cat. no. 1406.0.55.005).



Here is the same table with a range applied for the continuous values of 'Systolic Blood Pressure' (Systolic Ranged). Note that the numbers of respondents for the other responses 'Not applicable', 'Valid reading not obtained' and 'Not measured' no longer contribute to the table.

Any special codes for continuous data items are listed in the Data Item List.

Continuous items can be used to create custom categories in 'My Custom Data' by first ranging the item. For example, to create five year age groupings, this can be done by ranging the item with a five year increment. However, to deviate from groupings of equal increments, this must be done in 'My Custom Data'. As age is a continuous item, it must first be ranged (for example in one year increments) and then this ranged item can be grouped under the 'My Custom Data' tab to form unique age categories. For more information, see the 'My Custom Data' section of the User Manual: TableBuilder (cat. no. 1406.0.55.005).


CONFIDENTIALITY FEATURES IN TABLEBUILDER

In accordance with the Census and Statistics Act 1905, all the data in TableBuilder are subjected to a confidentiality process before release. This confidentiality process is undertaken to avoid releasing information that may allow the identification of particular individuals, families, households, dwellings or businesses.

Processes used in TableBuilder to confidentialise records include the following:

  • perturbation of data
  • table suppression
  • field exclusion rules.

Perturbation of data

To minimise the risk of identifying individuals in aggregate statistics, a technique is used to randomly adjust cell values. This technique is called perturbation. Perturbation involves small random adjustments of the statistics and is considered the most satisfactory technique for avoiding the release of identifiable statistics while maximising the range of information that can be released. These adjustments have a negligible impact on the underlying pattern of the statistics.

The introduction of these random adjustments result in tables not adding up. While some datasets apply a technique called additivity to give internally consistent results, additivity has not been implemented on this TableBuilder. As a result, randomly adjusted individual cells will be consistent across tables, but the totals in any table will not be the sum of the individual cell values. The size of the difference between summed cells and the relevant total will generally be very small.

Please be aware that the effects of perturbing the data may result in components being larger than their totals. This includes determining proportions.

Table suppression

Some tables generated within TableBuilder may contain a substantial proportion of very low counts within cells (excluding cells that have counts of zero). When this occurs, all values within the table are suppressed in order to preserve confidentiality. The following error message below is displayed at the bottom of the table when table suppression has occurred.

ERROR: The table has been suppressed as it is too sparse
ERROR: table cell values have been suppressed

Field exclusion rules

Certain groups of similar variables are restricted from being used together in a table. These restrictions are referred to as field exclusion rules, and are in place in order to protect confidentiality. The collection of similar variables restricted in this way are called field exclusion groups.

For the Australian Health Survey, there is one field exclusion group. This consists of the 2006 and 2011 geographical and Socio-Economic Indexes for Areas (SEIFA) data items (see below for items).

Only one data item from this group may be used in a single table.

The geographic exception to this is the State or Territory item, which can be used in addition to one item from this group.

Items included in the field exclusion group are:

2006 Geographic Items

  • ASGC remoteness area categories
  • Capital city and balance of state
  • Section of state

2011 Geographic Items
  • Remoteness area categories ASGS 2011
  • Greater Capital City Statistical Areas ASGS 2011
  • Section of state ASGS 2011
  • Medicare Locals
  • Peer Groups (MLs)
  • Primary Health Network

2006 SEIFA Items
  • Index of Economic Resources - 2006 - CD - Deciles - National
  • Index of Economic Resources - 2006 - CD - Deciles - State
  • Index of Economic Resources - 2006 - SLA - Deciles - National
  • Index of Economic Resources - 2006 - SLA - Deciles - State
  • Index of Education and Occupation - 2006 - CD - Deciles - National
  • Index of Education and Occupation - 2006 - CD - Deciles - State
  • Index of Education and Occupation - 2006 - SLA - Deciles - National
  • Index of Education and Occupation - 2006 - SLA - Deciles - State
  • Index of Relative Socio-economic Advantage and Disadvantage -2006 - CD - Deciles - National
  • Index of Relative Socio-economic Advantage and Disadvantage - 2006 - CD - Deciles - State
  • Index of Relative Socio-economic Advantage and Disadvantage - 2006 - SLA - Deciles - National
  • Index of Relative Socio-economic Advantage and Disadvantage - 2006 - SLA - Deciles - State
  • Index of Relative Socio-economic Disadvantage - 2006 - CD - Deciles - National
  • Index of Relative Socio-economic Disadvantage - 2006 - CD - Deciles - State
  • Index of Relative Socio-economic Disadvantage - 2006 - SLA - Deciles - National
  • Index of Relative Socio-economic Disadvantage - 2006 - SLA - Deciles - State

2011 SEIFA Items
  • Index of Economic Resources - 2011 - SA1 - Deciles - National
  • Index of Economic Resources - 2011 - SA1 - Deciles - State
  • Index of Economic Resources - 2011 - SA2 - Deciles - National
  • Index of Economic Resources - 2011 - SA2 - Deciles - State
  • Index of Education and Occupation - 2011 - SA1 - Deciles - National
  • Index of Education and Occupation - 2011 - SA1 - Deciles - State
  • Index of Education and Occupation - 2011 - SA2 - Deciles - National
  • Index of Education and Occupation - 2011 - SA2 - Deciles - State
  • Index of Relative Socio-economic Advantage and Disadvantage - 2011 - SA1 - Deciles - National
  • Index of Relative Socio-economic Advantage and Disadvantage - 2011 - SA1 - Deciles - State
  • Index of Relative Socio-economic Advantage and Disadvantage - 2011 - SA2 - Deciles - National
  • Index of Relative Socio-economic Advantage and Disadvantage - 2011 - SA2 - Deciles - State
  • Index of Relative Socio-economic Disadvantage - 2011 - SA1 - Deciles - National
  • Index of Relative Socio-economic Disadvantage - 2011 - SA1 - Deciles - State
  • Index of Relative Socio-economic Disadvantage - 2011 - SA2 - Deciles - National
  • Index of Relative Socio-economic Disadvantage - 2011 - SA2 - Deciles - State


WEIGHT VARIABLES

There are three weight variables visible on the TableBuilder file under Summation Options categories:
  • Households (Benchmarked Weight) - located on the Household level. This weight has been benchmarked to produce household estimates.
  • Persons (Benchmarked weight) - located on the Person level. This weight has been benchmarked to produce Australian population estimates for persons aged 2 years and over.
  • Biomedical persons (Benchmarked weight) - located on the Biomedical level. This weight has been benchmarked to produce Australian population estimates based on Biomedical participants aged 5 years and over. For more details on this weight, see below.

Using Weights

The NNPAS is a sample survey. To produce estimates for the in-scope population you must use weight fields in your tables. If you do not select a weight field, TableBuilder will use 'Persons (Benchmarked weight)' by default. This will give you estimates of the number of persons. To produce estimates of the number of households, you would have to change the weight field to 'Households (Benchmarked weight)' by adding it to your table from the Household level under Summation Options.

The Household Weight was benchmarked to the Household Level while the Person Weight was benchmarked to the Person level. To produce estimates for NNPAS persons who participated in the National Health Measures Survey (NHMS), the 'Biomedical persons (Benchmarked weight)' located on the Biomedical level must be used. When using a Weight/Summation from a level that is different to that of the variables in the table, please be careful in interpreting the results.

Level of Data itemExplanation of Estimates if use Person Weight for applicable population

1. Household level Persons in households with the specified characteristics.
2. Persons in household levelPersons in households containing one or more persons with the specified characteristics.
3. Person levelPersons with the specified characteristics.
4. Condition levelPersons with one or more conditions with the specified characteristics.
5. Child 2-4 Years Physical Activity levelPersons with one or more physical activity days with the specified characteristics.
6. Child 5-17 years Physical Activity levelPersons with one or more physical activity days with the specified characteristics.
7. Child 5-17 years Physical Activity Detailed levelPersons with one or more physical activity types with the specified characteristics.
8. Adult Physical Activity levelPersons with one or more physical activity types with the specified characteristics.
9. Pedometer levelPersons with one or more pedometer days with the specified characteristics.
10. Biomedical levelPersons with the specified biomedical characteristics.
11. Food levelPersons with one or more food days with the specified characteristics.
12. Supplement levelPersons with one or more supplement days with the specified characteristics.


Note that the Biomedical level contains non-biomedical participant records, however their biomedical weight is set to 0 so they will not contribute to estimates when the Biomedical persons (Benchmarked weight) is used. However, if the Persons (Benchmarked weight) is used with biomedical data items, then these non-participants will contribute to estimates. When using biomedical variables in conjunction with other variables on the Biomedical level or with variables from other levels, the Biomedical persons (Benchmarked weight) should be used.

For example, a table of reported 'Month of biomedical collection' using the 'Persons (Benchmarked weight)' will show the 'Month of biomedical collection' for the entire National Nutrition and Physical Activity Survey. Note that the 'Not applicable' persons include those people who did not participate in the NHMS. The population for this table presents the weighted estimates for the population aged 2 years and over.



The same table using the 'Biomedical persons (Benchmarked weight)' will show the 'Month of biomedical collection' for only persons who participated in the NHMS. Note that in this case, no-one is in the 'Not applicable' category. People who did not participate in the biomedical component do not have a biomedical person weight and therefore do not contribute to the table when this weight is used. The biomedical population now presents weighted estimates for persons aged 5 years and over.



You can use a weight field with classificatory fields from other levels, but should take care when interpreting the results. Below are some examples which you can use as a guide.

Weight FieldClassificatory FieldRelative Position of Data to WeightExample Estimate
Persons (Benchmarked weight)State or TerritoryAboveNumber of persons in NSW
Persons (Benchmarked weight)Sex of PersonSameNumber of Males
Persons (Benchmarked weight)Type of ActivityBelowNumber of persons who have participated in that activity type at least once


MEANS AND MEDIANS

Means, medians and sums of continuous data items are automatically calculated at the level of the continuous data item. Due to current functionality of the software, a weight from another level cannot be brought into such calculations. The "subject" of means, medians and sums calculated in TableBuilder is therefore the statistical unit associated with the level of the database on which the continuous data item is stored. The weights used for these calculations are not visible, other than on the Person level, but are referenced in the 'Weighted by' statement with continuous variables, as per:



Means, medians and sums across levels

Means, medians and sums of continuous items are automatically weighted before the mean, median or sum is calculated. As TableBuilder only allows one weight to be included in a table, all other items in the table will inherit the weight applied to the mean, median or sum. This has implications when using means, medians and sums from one level with items from another level. For example, if you cross tabulate "Weighted mean of Age" (a Person level data item) with "Total cholesterol status (mmol/L)" (a Biomedical level data item), the default weight applied to the table will be "Persons (Benchmarked Weight)" because this weight is automatically included in the mean "Age of person" calculation. As a result, the biomedical item, "Total cholesterol status (mmol/L)" will also be weighted to "Persons (Benchmarked Weight)" not "Biomedical Persons (Benchmarked Weight)".


ITEMS LOCATED ON MULTIPLE LEVELS

Where items are available on more than one level, an additional number is added to the label to indicate the level version. For example, a (1) indicates it is a Household level version, a (2) indicates a Persons in household level version, a (3) indicates a Person level version, and so on. These are identified in the Data item list labelling as well as the item in TableBuilder. The numbering is based on the ordering of levels found in the File Structure page of this product.

Care should be used to ensure the correct version of the item is used, particularly with regards to demographic items located on both the Persons in household and Person levels. See below for more details.


PERSONS IN HOUSEHOLD LEVEL VS PERSON LEVEL ITEMS

The Persons in Household level contains data for every person in the household while the Persons level only contains data for the selected persons. Both levels are children of the Household level - that is, they are siblings and are not linked by person but by household (see the File structure page of this product for further information on structure). This means that there is a many-to-many link between records at these levels (persons on the Person level are linked to all the people in their household on the Persons in household level). When summing the Person weight (which is stored at the Person level) the meaning of the estimates produced when disaggregating by another data item at the Person level will not be the same as the meaning of the estimates produced when disaggregating by a data item at the Persons in Household level.

For example, disaggregating by Sex and Marital status at the Person level will produce estimates of the type "Number of persons who are Male and Married". These estimates will be additive (aside from the effects of perturbation) as shown below.



On the other hand, disaggregating by Sex and Marital status at the Persons in Household level, and using the Persons (Benchmarked weight) from the Person level, will produce estimates of the type "Number of persons in households containing one or more persons who are Male and Married". These estimates will usually not be additive, as shown below.