APPENDIX 2 RE-REFERENCING THE WAGE PRICE INDEX
REFERENCE BASE
The reference base of an index series is that period for which the value of the index is set to 100.0. For the wage price indexes, the September quarter 1997 was used as the original reference base, as it was the first quarter for which data was available. With the introduction of the non-wage and labour price indexes, all indexes are now presented on a reference base of 2003-04.
CONVERTING A SERIES TO THE NEW REFERENCE BASE
The conversion of series from the old base to the new base involves a rescaling of the index numbers. The conversion factor that should be applied to the index numbers is calculated by obtaining the ratio of the index numbers on the old and new bases for the new reference period.
The conversion factor is calculated using the unrounded index number for the 2003-04 financial year. The calculation of financial year indexes is outlined in paragraph 34 of the Explanatory Notes.
For example, for the total hourly rates of pay excluding bonuses index for Australia, an arithmetic conversion factor is obtained as follows:
Index number for year 2003-04 (on base September quarter 1997 = 100.0) is 123.075
Index number for year 2003-04 (on base 2003-04 = 100.0) is 100.0
Conversion factor 100/123.075 = 0.8125
The factor 0.8125 may be multiplied by any total hourly rates of pay excluding bonuses index number for Australia on the old reference base to give the corresponding number on the new reference base. The procedure shown in the above example may be followed in respect of any specific index series for which index numbers have been published on the old reference base.
ROUNDING
Index numbers and percentage changes are always published to one decimal place, with the percentage changes being calculated from the rounded index numbers. Index numbers for periods longer than a single quarter (e.g. for financial years) are calculated as the simple arithmetic average of the relevant rounded quarterly index numbers. The conversion factor described above is applied to the rounded index numbers.
A consequence of re-referencing price indexes can be that period to period percentage changes calculated using re-referenced index number series may differ slightly from those calculated using the original series. These differences do not constitute a revision of the index but simply reflect the effect of rounding.
CONVERTING THE RE-REFERENCED SERIES BACK TO THE PREVIOUS BASE
The conversion of series from the new base to the old base also involves a rescaling of the index numbers. The rescaling factor is obtained by taking the inverse of the previously described scaling factor.
For example, for the total hourly rates of pay excluding bonuses index for Australia, the rescaling factor is obtained as follows:
Index number for year 2003-04 (on base September quarter 1997 = 100.0) is 123.075
Index number for year 2003-04 (on base 2003-04 = 100.0) is 100.0
Conversion factor 123.075/100 = 1.2308
The factor 1.2308 may be multiplied by any total hourly rates of pay excluding bonuses index number for Australia on the new reference base to give the corresponding number on the old reference base.
Conversion factors for most of the published total hourly rates of pay excluding bonuses indexes are provided in table A2. Additional factors can be obtained using the formulas above or by contacting David Taylor on Perth (08) 9360 5151.
CONVERSION FACTORS
A2 Factors used to convert index numbers, From old reference base (September quarter 1997 = 100.0) to new (2003-04 = 100.0) |
|  |
| | Private | Public | All sectors | |
| |
| Australia | 0.8175 | 0.7976 | 0.8125 | |
| Sector by state/territory | | | | |
| New South Wales | 0.8130 | 0.7765 | 0.8047 | |
| Victoria | 0.8167 | 0.8092 | 0.8152 | |
| Queensland | 0.8263 | 0.8010 | 0.8193 | |
| South Australia | 0.8168 | 0.7992 | 0.8119 | |
| Western Australia | 0.8155 | 0.8187 | 0.8165 | |
| Tasmania | 0.8365 | 0.8225 | 0.8319 | |
| Northern Territory | 0.8412 | 0.8132 | 0.8299 | |
| Australian Capital Territory | 0.8165 | 0.8168 | 0.8172 | |
| Sector by industry(a) | | | | |
| Mining | 0.8273 | . . | 0.8268 | |
| Manufacturing | 0.8078 | . . | 0.8079 | |
| Electricity, gas and water supply | 0.7949 | . . | 0.7803 | |
| Construction | 0.7979 | . . | 0.7982 | |
| Wholesale trade | 0.8304 | . . | 0.8304 | |
| Retail trade | 0.8457 | . . | 0.8455 | |
| Accommodation, cafes and restaurants | 0.8386 | . . | 0.8391 | |
| Transport and storage | 0.8372 | . . | 0.8316 | |
| Communication services | 0.8203 | . . | 0.8229 | |
| Finance and insurance | 0.8003 | . . | 0.8013 | |
| Property and business services | 0.7981 | . . | 0.7981 | |
| Government administration and defence | . . | 0.8055 | 0.8055 | |
| Education | 0.8073 | 0.7908 | 0.7960 | |
| Health and community services | 0.8239 | 0.7837 | 0.8056 | |
| Cultural and recreational services | 0.8290 | 0.8175 | 0.8256 | |
| Personal and other services | 0.8389 | 0.7900 | 0.8158 | |
| Sector by occupation(b) | | | | |
| Managers and administrators | 0.8100 | 0.7998 | 0.8076 | |
| Professionals | 0.7998 | 0.7896 | 0.7959 | |
| Associate professionals | 0.8237 | 0.7971 | 0.8160 | |
| Tradespersons | 0.8187 | 0.7970 | 0.8157 | |
| Advanced clerical and service workers | 0.8266 | 0.7997 | 0.8229 | |
| Intermediate clerical, sales and related workers | 0.8256 | 0.8053 | 0.8205 | |
| Intermediate production and transport workers | 0.8261 | 0.8066 | 0.8241 | |
| Elementary clerical, sales and service workers | 0.8395 | 0.8035 | 0.8321 | |
| Labourers and related workers | 0.8280 | 0.7981 | 0.8239 | |
| |
| . . not applicable |
| (a) Classified according to Australian and New Zealand Standard Industrial Classification (ANZSIC), 1993 (cat. no. 1292.0). |
| (b) Classified according to the Australian Standard Classification of Occupations (ASCO), Second Edition (cat. no. 1220.0). |
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