County of Middlesex POPULATION PROJECTION, 2001 - 2026 TABLE OF CONTENTS PAGE NO. 1.0 INTRODUCTION .................................................................................... 1 2.0 POPULATION PROJECTIONS - METHODOLOGY ........................ 1 2.1 THE COHORT-SURVIVAL POPULATION PROJECTION METHOD .................. 1 2.2 LIMITATIONS OF THE CENSUS DATA ........................................................ 2 2.3 POPULATION PROJECTIONS FOR CONSTITUENT MUNICIPALITIES .............. 3 2.4 LIMITATIONS OF THE POPULATION PROJECTIONS ...................................... 4 3.0 POPULATION PROJECTIONS - RESULTS ...................................... 4 3.1 GROWTH RATES AND PATTERNS .............................................................. 4 3.2 FORECASTS- LOW, REFERENCE AND HIGH SCENARIOS .......................... 11 4.0 HOUSEHOLD SIZE .............................................................................. 16 4.1 NATIONAL TRENDS ................................................................................ 16 4.2 PROVINCIAL TRENDS ............................................................................. 16 4.3 COUNTY OF MIDDLESEX AND AREA TRENDS ......................................... 17 APPENDIX A Detailed Projections, County of Middlesex and its Constituent Municipalities, Low, Reference and High Scenarios APPENDIX B Detailed Tables, County of Middlesex and its Constituent Municipalities, Reference Scenario, Births, Deaths, Migration APPENDIX C Place of Work, County of Middlesex and its Constituent Municipalities I-18493 i County of Middlesex POPULATION PROJECTION, 2001 - 2026 1.0 INTRODUCTION The County of Middlesex periodically prepares twenty-five year population projections. As new Census data becomes available, projections have been prepared for successive periods using a consistent cohort survival projection approach for the County and its constituent municipalities. Previous projections utilised statistics from the respective 1986, 1991 and 1996 Census. Now, with the availability of Census data for 2001, forecasts for the 2001 to 2026 period have been prepared which reflect population trends in the County up to 2001. 2.0 POPULATION PROJECTIONS - METHODOLOGY 2.1 THE COHORT-SURVIVAL POPULATION PROJECTION METHOD Population projections for the County and the eight constituent communities were prepared using a composite cohort survival population projection method. The sum of these projections comprise the projection for the County. The spreadsheet used calculates a population projection using a modified cohort-component technique and five year projections are produced as intermediate estimates. Composite projections describe the direction and magnitude of the variables that affect population change. They are based on the theory that population can increase in only two ways: natural increase and net migration. The more sophisticated models provide estimates of the natural increase and net migration not just for the aggregate population, but for age cohorts within the population and this technique is usually called the "cohort survival method”. This is the technical analysis and method used for this current study and is consistent with those studies previously undertaken. A cohort survival method ages the population of a municipality one-year at a time (incorporating age specific fertility and mortality rates), and adjusts this demographic projection with migration assumptions. It is a reasonable approach for areas with a larger population base such as the County as a whole as it allows a detailed assessment of the factors affecting population growth and permits a study of the implications of changing conditions. The advantage to using a cohort model is that the causal dynamics underlying population change can be better understood which allows the model to deal with forces of change. For instance, these models make finer distinctions of which age groups are changing in the population mix. This finer-grained analysis is frequently very useful in estimating (for example) future demands for specific services. The model can be unwieldy however, as it requires a large number of assumptions which are difficult to quantify for smaller geographic areas or for very small population areas. This “instability” can be mitigated as the model can be manually adjusted to account for locationally-specific conditions. Therefore, the study relies on County Staff and their local knowledge to direct the assessment of some direct or imputed assumptions that are necessary for cohort survival analyses. I-18493 1 County of Middlesex POPULATION PROJECTION, 2001 - 2026 In its basic form, the cohort-survival method is very simple: Population in the future = Current Population + Natural Increase + Net Migration The sections that follow give some detail regarding how these three elements interact to mathematically produce a forecast of population. Current Population In a cohort survival method of analysis, the time interval that is projected is determined by age cohorts. The smallest time interval for which an estimate can be made is the length of time it takes all the members of an age cohort (say, everyone age 10 - 14) to pass on to the next age grouping (the 15 - 19 year-old group). Since Statistics Canada commonly aggregates their population figures in five-year cohorts, most cohort survival models run at five-year projection increments. The cohort model includes, as inputs, 10 years’ worth of historical population data for the constituent municipalities of the County. The output provides a twenty-five year forecast for those municipalities. The County forecasts are simple aggregations of these projections. Natural Increase Natural increase is the difference between the number of children born and the number of people who die during one time interval. Children can only be born into the 0-4 year cohort. People, however, die in all cohorts. Briefly, the model employs a survival rate to calculate how many persons will likely die in each cohort as the population ages. Further, the model employs a birthrate that estimates the number of babies born as the original municipal populations age. Since births and deaths statistics are not usually readily available at the local level (i.e. data is collected by Health Units that generally do not match Statistics Canada dissemination area boundaries), the study utilises the birth rate and death rate as that generated in the Province over the 1991 to 2001 period. The advantage to using the Provincial rate is that it is based on a large, stable population which may better represent births and deaths over the relatively long planning horizon. Net Migration Net migration is the difference between the number of people moving in and the number of people moving out. The model employed in this analysis simply assumes that the difference between the calculated number of survivors for a given cohort over the 1991 to 2001 period and the actual number of people in that cohort counted by the Census is the net number of migrants. Like all rates and variables in this model, this figure is calculated at the cohort level 2.2 LIMITATIONS OF THE CENSUS DATA As discussed in the introduction to this study, Census data provided by Statistics Canada was used in the preparation of the population forecasts that follow. I-18493 2 County of Middlesex POPULATION PROJECTION, 2001 - 2026 The data used is presented by male and female populations categorised by five year age cohorts for the individual communities and the County. There are two important limitations inherent in this data. First, the population of any native reserves have not been included in the population forecasts as these data are not consistently reliable in the various statistics provided by Statistics Canada. Second, the Census data, on a cohort basis, is not 100% “accurate”. For reasons of confidentiality, cohort-specific populations are reported on a “randomly rounded” basis. It is not an important consideration with very large populations, but for many small communities this means that the reported population could be “out” by perhaps as many as about 180 people. It is important to note that this is not an insignificant figure when considering the fact that, for example, the population of Newbury in 2001 is reported at 395 people. It is also important to realise that these “inaccuracies” can be unknowingly amplified over time through the use of projection models. Consequently, those projections for all the small communities that make up the County of Middlesex (i.e. Newbury), must be viewed with utmost caution. 2.3 POPULATION PROJECTIONS FOR CONSTITUENT MUNICIPALITIES Population projections for the eight constituent municipalities were prepared and aggregated to forecast the County’s population under three different scenarios; • Low Scenario – Considers an aggregated County population in 2026 that is consistent with the total current 2001 County population. • Reference Scenario – This scenario utilises the current population trends in the constituent municipalities. The projection also considers the effect that migration patterns may have on the County. The Ministry of Finance projects that Middlesex County will grow by 0.4% annually but, importantly, this includes the City of London. The most notable feature of the Ministry projection that has some bearing on the current County forecast is the doubling in population of the 60 to 64 age group by 2028. Currently, according to the Ministry, this age group in the County (which includes London),