Ready-mixed concrete

3 Quarterly

Seasonally adjusted and trend series were added in the September 2018 quarter, along with new time series identifiers.

The Quarterly Ready-mixed Concrete Production survey began in 1963. Throughout the years the survey hasn't had any major changes in the survey design. However, there have been slight changes made to the regional categories in the one page releases, such as the inclusion of metropolitan areas from the December 1987 quarter onwards.

In 1995, it was decided to change the classification of the regions. Previously regions were classified by the Ready Mixed Concrete Association to which respondents belonged. Due to the limited usefulness for research purposes it was decided to use local government regions. Statistics for the new regions were calculated back to the March 1992 quarter.

The earliest data for the Ready-mixed Concrete Production Survey is the New Zealand Total which is stored on Infoshare from the March 1992 quarter onwards. The series reference on Infoshare is SEP under Industry sectors/ Secondary production.

From the first quarter in 1993, the Auckland ready-mixed concrete production data was extracted from the Ready-mixed Concrete survey, two weeks earlier than Ready-mixed Concrete Production release. The production figures in the Auckland release are the same as those in the main release for the Auckland region.

Seasonally adjusted series

Seasonal adjustment removes the estimated effect of regular seasonal events, such as summer holidays and pre-Christmas purchasing, from statistical series. This makes figures for adjacent periods more comparable. The seasonally adjusted series are revised each quarter. We use the X-13 ARIMA-SEATS seasonal adjustment program, developed at the US Census Bureau, to produce the seasonally adjusted and trend estimates.

When the COVID-19 pandemic hit in 2020, we manually specially treated unusual data (outliers) to prevent them from impacting the seasonally adjusted series. For total ready-mixed concrete production, we applied additive outliers (AO) to two quarters: June 2020 and September 2021.

In the March 2023 quarter, we replaced manual with automatic AO from March 2020 quarter onwards, using less cautious criteria. For total ready-mixed concrete production, the June 2020 and September 2021 quarters remain as outliers under automatic AO detection, with minimal change to the seasonally adjusted series. We also removed trading-day adjustments as they were unnecessary.

Seasonal adjustment and automatic outliers in time series after COVID-19 has more information.

In conjunction with production information collected on the other commodities, provides important economic indicators for the whole economy and regional areas. Individual firms also use statistics for market research.

Concrete Industry Reserve Bank of New Zealand