The Demopædia Encyclopedia on Population is under heavy modernization and maintenance. Outputs could look bizarre, sorry for the temporary inconvenience
Multilingual Demographic Dictionary, second unified edition, English volume
40
Disclaimer : The sponsors of Demopaedia do not necessarily agree with all the definitions contained in this version of the Dictionary. The harmonization of all the second editions of the Multilingual Demographic Dictionary is an ongoing process. Please consult the discussion area of this page for further comments. |
Go to: Introduction to Demopædia | Instructions on use | Downloads |
401
The study of mortality ^{1} deals with the effect of death on the population. The general terms mortality rate ^{2} or death rate ^{2} encompass all the rates (133-4) which measure the frequency of deaths ^{3}. Where the expression death rate is used without any qualifying adjective the crude death rate ^{4} is usually meant (cf. 136-8 for a general discussion of crude rates). This is generally an annual rate and consists of the ratio of the annual number of deaths occurring during a calendar year to the number exposed to the risk of dying during the same period. This number is equivalent to the mean population ^{5} or average population ^{5} for the period, and the population at the mid-point of the period can usually be substituted for the average population without appreciable error, if the size of the population is changing fairly uniformly. If the mortality of a sub-population (101-6) only is studied, we speak of specific death rates (134-6) among which sex-age-specific death rates ^{6} are the most common. Age specific death rates ^{7} without distinction of sex are also used on occasion.
- 2. Occasionally the term mortality is used as a synonym for mortality rate or death rate.
- 3. Death, n. - die, v. - dead, adj. syn. - deceased, adj. or n.
- 5. When the observation period exceeds one year, the mean population is generally obtained as the average of several estimates of the size of the population for each year. The average number of persons years (135-6) is also used as denominator.
402
Specific death rates may be used to study differential mortality ^{1} or mortality differences ^{1} between groups, and reference is made to an excess mortality ^{2} of one group as compared with another, or with the rest of the population. It is measured by an excess mortality index ^{3★}. The study of differences in the death rates of specific occupations is called the study of occupational mortality ^{4}. In a rather different sense the term occupational mortality ^{5} may refer to the mortality from hazards associated with a particular occupation. Among these, we may mention occupational diseases ^{6}.
- 1. Differentials in mortality is also encountered.
- 2. The expression excess male mortality implies a comparison with the corresponding female mortality, e.g. at the same age.
403
Crude death rates (401-4) will depend upon the structure [particularly the age structure (325-6)] of the population as well as on the level of mortality. If the mortality of different populations is to be compared standardized mortality rates ^{1} or adjusted mortality rates ^{1} are sometimes computed to eliminate the effect of differences in population structure (144-4). Age is the characteristic for which mortality rates are adjusted most frequently by reference to a standard population ^{2} with a given structure. If specific rates (134-6) for the population studied are available, it is possible to use the direct method of standardization ^{3} which consists of applying these rates to the corresponding groups of the standard population. If specific rates are not available, it is still possible to obtain standardized mortality rates by the indirect method of standardization ^{4}. More frequently, comparative mortality indices ^{5} are computed by applying standard mortality rates ^{6} to the different groups of the population studied and summing these to obtain an expected number of deaths; the indices are then obtained by comparing the observed deaths ^{7} in the population with the expected deaths ^{8} which would have occurred had the standard rates applied.
- 1. Standardize, v. - standardized, adj. - standardization, n.: the process of standardizing.
- 5. If a crude death rate (401-4) is multiplied by a comparative mortality index, we obtain an indirectly standardized death rate. In British official terminology, when occupational mortality is studied, the figure obtained by direct standardization is called a comparative mortality figure and that obtained by indirect standardization a standardized mortality ratio.
* * *
Go to: Introduction to Demopædia | Instructions on use | Downloads |