For the Record
On projected population growth
This article seeks to clarify some issues on population statistics recently printed in some of the major dailies, specifically the following:
From the NSCB press release posted in the NSCB website on May 9, 2006, Philippine population growth slows to 1.95 percent by 2010 :1
The population growth rate of 1.95 percent represents the projected average annual rates of increase for the period 2005-2010. This figure was derived from the 2000-Census of Population-based population projections using the medium set of assumptions described in the methodology below. Users are therefore cautioned that the figures should be interpreted as most likely to happen in the period 2005-2010 given certain assumptions, and hence, should not be misinterpreted as something that has already happened.
Population projections are used to provide planners, policy-makers and program managers with data for medium- and long-range planning, and for estimates of population between census years.
Brief on methodology for population projections at the national level
For a better understanding of the methodology used in preparing the population projections, below is a brief description:
The 2000 Census-based population projections utilized the Cohort-Component Method which involves projecting the levels and trends of fertility, mortality and migration, as follows:
Assumption of fertility: For future trends of fertility, three assumptions were made based on the time when replacement-level fertility, that is, net replacement rate (NRR) =1.0 will be attained. For the LOW series (rapid pace of fertility decline or low levels of fertility), NRR=1.0 was targeted for the year 2030. For the MEDIUM series (moderate pace of fertility decline or moderate fertility levels), NRR=1 was targeted for the year 2040 and for the HIGH series (slow pace of fertility decline or high fertility levels), NRR=1.0 by 2050.
An NRR of 1 means a level of fertility at which a population exactly replaces itself from one generation to the next. This is equivalent to a total fertility rate (TFR) of 2.1. TFR is the average number of children that would be born alive to a woman (or group of women) during her lifetime if she were to pass through her childbearing years (15-49) conforming to the age specific fertility rates of a given time period.
The 2000 Census-based projections released in the website refer to the medium series.
Assumption of mortality: The mortality indicator life expectancy at birth, exo for the projected periods follows that of the UN Working Model for quinquennial gains in life expectancy, that is, for a developing country like the Philippines, about 2 years improvement in life expectancy per 5 years is plausible. This also means the present government health programs are continued and improved with an increase in resource allocation.
Life expectancy at birth refers to the number of years a newborn child can be expected to live under a given mortality condition of an area in a given year.
Assumption of migration: International migration was considered negligible since, based on the assessment of the Technical Committee on Population and Housing Statistics, it still has little effect on the national total population. However, further studies will be undertaken to establish more sound basis for estimating international migration trends.
The above assumptions were made on the basis of historical trends from the National Demographic and Health Surveys (NDHS: 1998, 2003), the Census of Population (CPH: 1990, 1995, 2000), the Census of Population (PopCen: 1995), the Family Planning Surveys (FPS: 1995-1997, 1999-2002), the vital statistics from the civil registration system, as well as inputs from the government health programs. For example, fertility data from the NDHS gives decreasing total fertility rates from 3.72 based on the 1998 NDHS to 3.52 based on the 2003 NDHS. Likewise, trends in contraceptive prevalence rate (the proportion of currently married women in the reproductive ages of 15-49 years reporting current use of any contraceptive method) shown by FPS and NDHS data were generally increasing from 46.5 percent in 1998 to 49.3 percent in 2004.
The NSCB would like to stress that the official figures for population projections are generated by the National Statistics Office through the Inter-Agency Working Group on Population Projections. The methodology used for the generation of these projections was endorsed by the Technical Committee on Population and Housing, and consequently approved by the NSCB Executive Board.
Under the system of designated statistics per Executive Order No. 352, Designation of Statistical Activities that will Generate Critical Data for Decision-Making of the Government and the Private Sector issued on July 1, 1996, the methodology for preparing the population projections is designated to the NSCB through the Technical Committee on Population and Housing Statistics currently chaired by Dr. Mercedes B. Concepcion, while the generation of the estimates is designated to the National Statistics Office. The preparation of population projections is a designated statistical activity to be done after every Census year as mandated.
Please refer to the detailed documentation of methodology in the technical annex to NSCB Board Resolution Number 7 series 2006, A Brief Description of the Methodology for the 2000-Census-Based Population Projections in http://www.nscb.gov.ph/resolutions/2006/7Annex.pdf .
For inquiries, please contact Ms. Fe Vida N. Dy-Liacco or Ms. Marymell Martillan at telephone numbered (632) 890 9678 or through e-mail addresses firstname.lastname@example.org and email@example.com.
1Because of the confusion in the media, the headline has been changed to “Philippine population growth expected to slow down to 1.95 percent in 2005-2010”.
2 The figures are three-year averages centered on 1996 and 2001, respectively.