Data Explanation

The Canadian Human Mortality Database (CHMD) includes the following types of data:

• live birth counts,
• death counts,
• population size on January 1^st,
• population exposed to risk of death,
• death rates,
• life tables, and
• life expectancy at birth.

Format of the data

• All CHMD data files are tab-delimited text (ASCII) files
• Population size is given for one-year¹ and five-year² age groups.³
• Deaths are given in the following formats:³
  • Lexis triangles (i.e., by age¹, birth cohort, and calendar year)
  • 1x1 (i.e., by age¹ and calendar year)
  • 5x1 (i.e., by 5-year² age group and calendar year).
• Exposure-to-risk, death rates, and life tables are given in similar formats of age and time:
  • 1x1 (i.e., by age¹ and year)
  • 1x5 (i.e., by age¹ and 5-year time interval)
  • 1x10 (i.e., by age¹ and 10-year time interval)
  • 5x1 (i.e., by 5-year² age group and year)
  • 5x5 (i.e., by 5-year² age group and 5-year time interval)
  • 5x10 (i.e., by 5-year² age group and 10-year time interval).

¹ One-year age groups (or "by age") means 0, 1, 2, ..., 109, 110+.
² Five-year age groups means 0, 1-4, 5-9, 10-14,..., 105-109, 110+. Age groups are defined in terms of completed age, so "5-9" extends from exact age 5 to just before the 10^th birthday.
³ Some of these numbers are estimates (not actual counts), and therefore may be expressed as non-integers.

The following columns are included in each life table:

Year	Year or range of years
Age	Age group for n-year interval from exact age x to just before exact age x+n, where n=1, 4, 5, or ∞ (open age interval)
m(x)	Life table death rates between exact ages x and x+n
q(x)	Probability of death between exact ages x and x+n
a(x)	Average number of person-years lived between exact ages x and x+n
l(x)	Number of survivors at exact age x, assuming l(0) = 100,000
d(x)	Number of deaths between exact ages x and x+n
L(x)	Number of person-years lived between exact ages x and x+n
T(x)	Number of person-years remaining after exact age x
e(x)	Life expectancy at exact age x (in years)

See the Methods Protocol (pg. 34-42) available on the Human Mortality Database's web site for more details about life table calculations.

Important Notes

• Deaths, population estimates, death rates, and life tables are provided by single years of age up to 109, with an open age interval for 110+. However, these data are sometimes the product of aggregate raw data (e.g., open age intervals at 100 years old and over), which have been split into single years of age using the methods described in the Methods Protocol.
• Since the population of Canada encountered a territorial change in 1949 with the addition of Newfoundland and Labrador in the Canadian Confederation, two sets of population estimates are given for January 1^st 1949. The first set of estimates (identified as year "1949-") refers to the population just before the territorial change, while the second set (identified as year "1949+") refers to the population just after the change.
• For all life tables, the central death rate m(x) is used to compute probabilities of death q(x). By definition, the values of m(x) below age 80 are equal to the observed population death rate M(x). At older ages, however, the number of deaths and the exposure-to-risk eventually become quite small, and thus observed death rates display considerable random variation. Therefore, the values for M(x) at ages 80 and older are smoothed and then used to compute q(x) above a certain age (based on the number of observed deaths). This procedure helps to avoid certain difficulties in life table calculations at older ages that may be caused by:
  • extremely high death rates resulting from exposure being smaller than the number of deaths,
  • death rates of zero resulting from no deaths at an age where exposure is non-zero, and
  • undefined death rates at all ages where exposure is zero.

NOTE: The text above has been adapted from the Human Mortality Database web site (www.mortality.org).