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The 2013 Census and changes in the distribution of population within and between the City and Districts of Greater Christchurch City. James Newell, MERA ( Monitoring and Evaluation Research Associates Ltd) March 13th, 2014 Seminar. Scope.
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The 2013 Census and changes in the distribution of population within and between the City and Districts of Greater Christchurch City James Newell, MERA (Monitoring and Evaluation Research Associates Ltd) March 13th, 2014 Seminar
Scope • Working with Stats NZ 2013 Census population composition results for suburbs (area units) released Tuesday • Putting statistics on the changes for each suburb online using an evolving custom inhouse toolkit • Adding value to the raw census data and complementing the seminars? • Discussing the first set of Au200613 data online • Limitations of area units – NE Chch and Rolleston • Some migration results from earlier work • Directions.
Outline • Stats NZ 2013 Census stats on suburbs (area units) • How to add value to the seminars and use the area unit data – putting statistics, indicators, statistical graphics, series online • Looking at the first indicative Au200613 pages online • Limitations of area units are shown – NE Chch and Rolleston • Some useful related results from recent earlier work
Recent releases • Stats NZ 2013 Census releases some results for area units within Greater Chch • 18th Feb in Quick Stats on Greater Chch • 11th March in NZ.Stat population tables • In general, the actual detail of 2013 census releases something that only discover on the day… • Online statistics on the Christchurch recovery.. • Building some trend summaries for area units online from this Tuesday’s first major area unit level stats release
Outline • Stats NZ 2013 Census releases some results for area units within Greater Chch • 18th Feb in Quick Stats on Greater Chch • 11th March in NZ.Stat population tables • In general, the actual detail of 2013 census releases is something that only discover on the day… • Putting this together with other census data… • Net Migration • Internal migration flows by age • External (International) Migration flows update • Online statistics on the Christchurch recovery..
Working with groups of 2013 & 2006 area units • Most of the legacy data on AU2006 • Join with new statistics on 2013 geography as it comes available • Group the data to AU200613 as a starting point .. For the moment • Release of 2013 Census meshblock database will vastly increase the ease of linking 2013 and earlier data • Refer to the MERA online classification page on the new online MERA ‘socioecometrica’ info library (http://socioecometrica.co.nz/index.php)
An example of an AU200613 • Main Directory to 2006 / 2013 Area Unit Groups is at the url • http://socioecometrica.co.nz/InfoLib/NZAU/AU200613A_DirectoryPageV1a.php Only Canterbury pages are currently loaded and links operational ..
What is on each AU200613 page so far? • Area unit group population summary for the 1981 to 2013 period • Comparison of annual % growth rate for census periods from 1981 to 2013 to the containing • “ward”, “community board”, local authority and regional TLA grouping and NZ • List of 2013 and 2006 area units in each 200613 area unit grouping • Population pyramid showing 2006 and 2013 and % change 2006/2013 for each age group • Age composition by 5 yr age group 1981 to 2013
“Rolleston” – Annual % Change in usually resident population by period
Rolleston – Comparing 2006 and 2013 Population age composition ..
Online library and analysis not just about census • TLA (Local Authority) Pages also hold graph of adjusted PLT (permanent long term) migration • In terms of arrivals and departures expressed as a 12 mth moving average • Adjustment is a pro-rata type location of arrivals and departures where orgin or destination TLA or region was not defined
Online library – not about data about information • Value added to data • Derivatives • Specialised statistical graphics, maps • Integration of census and other sources .. • Wholistic place based view ..
Scope – direction for future development .. • Standardise summary comparisons of each geographic unit with all other “higher” geographic level units • For example – area compared with the region or NZ … • More work on indexing and cross links • More specialised well selected graphical representations of information • Main page for each geographical area (or “place”) to act as a summary page with other link pages with specialised detail for different subjects • eg. Household composition, labour market / jobs / industries, projections ..…
Scope – direction for future development .. • Wider range of geography summary layers • Community boards, CERA social monitoring districts, wards, community profile areas, community of interest areas, water catchment areas, labour market catchment areas … • Metadata pages and series specifications links for each set of data
SNZ Estimated % change in usually resident population – June Yrs – 2007-2013
Migration – an indicator of population redistribution and key driver of population projections • Key assumption – driver – migration • Last census provides key evidence of recent migration behaviour • Processes are scale and level as well as age and sex… dependent • Different migration processes at different levels – GtrChch, TLA and within TLA • Include residential capacity / demand behaviour assumptions at suburb level .. • Translate population in numbers of households / dwellings • Project future migration assumptions • base on a long term view • accounting for cyclical and one off events (eg. Earthquake effects)
Problems – the 7 yr gap – challenges for estimating migration movements .. • Census uses the question – what was your residential address five years ago (assumed to be the time of the previous census) • Designed to sync with the five year period since the last census • But it is now 7 years since the last census • It will generate some headaches in preparing estimates of trends in migration flows and migration rates – as needed to do new population projections • Statistics NZ 2013 census based projections at TLA level will be in late 2014 and into 2015 for more localised suburb level projections
Analysing trends …Migration Transitions by Greater Chch TLA and aggregated age group1976 … 2013
Working census migration – migration transitions • Migration address five years ago – provides a statistic on migration transitions between successive years … • What do the current migration results represent in the context of long term trends • What is period specific (eg EQ effects), what is long term trends of change, what are likely future migration transition rates • Evidence towards setting credible for future migration assumptions and corresponding projection scenarios
Census 2013 Migration data • It is complex– different processes at area unit, TLA, Regional and National Levels • Integrate those early 2013 Census results into a time series with results from previous census • Time series a TLA by TLA by 5 yr age and sex • Aggregate /select data from 2013 stats and legacy time series to a coherent time series on a common basis
Christchurch to Selwyn DistrictNet Migration Flows by Age & Period
Christchurch to Waimakariri DistrictNet Migration Flows by Age & Period
Permanent Long term Migration Flows – 12 mth moving average – Chch City to Dec 2013
Greater Christchurch - Long Term International Migration – 12 mth moving average
Which Country Group are the additional External Migrants coming from?
Effect of the Chch EQ on international long term migration flows – to date • Comparing relative rates of international long term migration – Chchvs North Island … • Differential migration arrivals / departures for Chch • Decreased departures effect peaked in December 2012 – April 2013 • Increase in arrivals has been peaked over Feb 2013 to July 2013 (Sept 2013 effect small…)
Estimate change in population of Greater Christchurch from Long Term International Migration effect of the EQ
Recovery Momentum : Number of Residential Building Consents – by Month to August 2013
Recovery Momentum : Number of Residential Building Consents – 12mths moving average by Month to August 2013
Spatial scales and change in Greater Christchurch– large localised changes in population size and composition at community level
Effects of the EQ on population change at different scales … • At Greater Christchurch level • Moderate population loss and subsequent recovery • At TLA level • More dramatic effects – especially intense increased development pressure and growth Selwyn District, some population loss for Christchurch City … • At suburb / community level • Very large rapid changes – increase and decreases within each TLA – community rebuilding / adaptation
Greater Christchurch – Years 1 to 5 of schooling (roughly 5-9 year olds)
Waimakariri & Selwyn Wards– Years 1 to 5 of schooling (roughly 5-9 year olds)
Christchurch City 2013 Wards– Years 1 to 5 of schooling (roughly 5-9 year olds)
Ethnicity and change in Greater Christchurch- different types, scale, distribution and timing of change for different ethnic communities
Maori Ethnicity - Year of Schooling 1 – 5 : Chch City by Ward
Pasifika Ethnicity - Year of Schooling 1 – 5 : Chch City by Ward
Asian Ethnicity - Year of Schooling 1 – 5 : Chch City by Ward
Summary of progress – and looking forward • Seminars are useful as a way of discussing work but limited in the ability to deliver communicate detail • Developed a toolkit to convert results onto a rich cross linked system on the internet or an intranet • Started to develop particular indicators in graph form suited to particular things – eg. Population pyramid comparisons, external PLT migration flows .. • Ready just in time to join the first lot of 2013 area unit population compositional data with earlier data and publish on the web • Part way through estimates of net migration transition rates for 1981-86 through to 2006-2013 using single year of age data to manage 7 year lag 2006 to 2013 • 2013 Meshblock data opens up a much wider range of attributes than available so far and also makes it easier to integrate 2013 and 2006 geographies and estimate results / profiles for community of interest” areas which are defined for meshblocks. • Come back again on the 4th to talk data more than systems, to look at the land use change for the 2006 to 2013 period integrating jobs, households, population, ethnic communities by area