**GLOSSARY**

**ABS**

Australian Bureau of Statistics.

**Aggregation**

The process of combining lower level price indexes to produce higher level indexes.

**ASGC**

**Australian Standard Geographical Classification (ASGC)** (cat. no. 1216.0). This is the standard geographical classification used in the ABS.

**CPI**

Consumer Price Index - a general indicator of the rate of change in prices paid by households for consumer goods and services.

**Cluster**

A suburb or, more commonly, a group of suburbs that have similar characteristics and for which medians are estimated each quarter and aggregated to produce the HPI for each city (they are similar to an “elementary aggregate” in other ABS price indexes).

**Component**

A level of like items within a price index structure.

**Elementary aggregate**

The lowest level of commodity classification in ABS price indexes and the only level for which index numbers are constructed by direct reference to price data. In the case of the HPI, this relates to individual clusters.

**Fixed-weight index **

A price index in which the weighting pattern is fixed for the life of each index series.

**HPI**

The established house price index. The term is usually used in describing the price index of established houses but it should be noted that the ABS publication **House Price Indexes: Eight Capital Cities** (cat. no. 6416.0) contains series other than those relating to established houses.

**Indexation**

The periodic adjustment of a money value according to changes in a price index.

**Index points change**

The change in an index number series from one period to another expressed in terms of the difference in the number of index points in each of the index numbers.

**Index points contribution **

A quantitative expression of how much each component contributes to the magnitude of the upper level index number.

**Index number series**

A series of numbers measuring the change over time from a reference base period value, which is normally presented as an index value of 100.0.

**Index reference period**

The period in which an index series is given a value of 100.0. Also referred to as reference base. The index reference period should not be confused with the weighting base period - see “Weight reference period” below.

**Inflation (deflation)**

A term commonly used to refer to changes in price levels. A rise in prices is called inflation, while a fall is called deflation.

**Linking**

The technique used to join a new index series (e.g. one having a changed composition and/or weighting pattern) to an old index series to form a continuous series. The technique ensures that the resultant linked index reflects only price variations and that introducing the new items and/or weights does not affect the level of the index.

**Link factor **

A ratio used to join a new index series to an old index series to form a continuous series.

**Matched sample**

In a matched sample, items that are priced from period to period are identical in all respects or sufficiently similar to be considered the same item.

**Percentage change**

The change in an index series from one period to another expressed as a percentage of its value in the first of the two periods.

**PPI **

Producer price index.

**Price index**

A composite measure of the prices of items expressed relative to a defined base period.

**Price levels**

Actual money values in a particular period of time.

**Price movements (or price changes)**

Changes in price levels between two or more periods. Movements can be expressed in money values, as price relatives or as percentage changes.

**Price relative**

The ratio of the price level in one period to the price level in an earlier period.

**Price update**

To revalue (inflate or deflate) a value using a measure of the price change between two periods.

**Principal Component Analysis**

A statistical method used in constructing the HPI stratification that determines which variables explain the variation in the price of houses (i.e. the principal components).

**Quality adjustment**

The elimination of the effect that changes in the quality or composition of an item have on the price of that item in order to isolate the pure price change.

**RBA **

Reserve Bank of Australia.

**Sample**

A representative selection of items to be priced, that acts to represent all items.

**SD**

Statistical Division, as determined in the Australian Standard Geographical Classification (see "ASGC"). In the HPI, each capital city is defined as those houses contained within the relevant statistical division.

**SSD**

Statistical Subdivision, as determined in the Australian Standard Geographical Classification (see "ASGC"). In the HPI, each cluster is geographically bounded within a statistical subdivision.

**SEIFA**

**Socio-economic Index for Areas** (cat. no. 2039.0). The SEIFA ranks geographic areas according to their social and economic conditions.

**Splicing **

A technique used to introduce new items into the index calculations so that the level of the index is not affected.

**Transaction price**

The price actually paid by a purchaser of a good or service - as opposed to a 'list' or 'quoted' price.

**Value aggregate**

The aggregate value in dollars of the housing stock (including land). In compiling the HPI, value aggregates serve as value weights which are updated each quarter using the price relatives for each cluster.

**VGs**

Valuers-General or equivalent government bodies in each state/territory responsible for the recording of property transfers.

**Weight**

The measure of the relative importance of an item in the index structure. Weights can be expressed in either quantity or value terms. Value weights are used by the ABS in compiling all official price indexes.

**Weighted average**

An average that is obtained by combining prices or price indexes according to the relative importance of each price index.

**Weight reference period**

The period to which the fixed quantity weights relate. (See also “Index reference period”.)

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