That is, persons under 5 form 13.6 per cent. of the total populations; persons aged 5 to 35 form 759 per cent.; and persons aged 55 and upwards form 10.5 per cent. Since 1883 the Registrar-General, in his annual summaries for London and other great towns, has given the corrections which must be applied to the death-rates for age and sex distribution, so as to make the urban death-rates comparable with that of the country (England and Wales) as a whole. Out of the 28 towns, the correction adds in 26 a certain quantity to the recorded rate, varying from 0.5 to 3 per 1000; whilst in two towns-Norwich and Plymouth-a small subtraction must be made from the recorded. rates. The correction for London is + 1.3 per 1,000; or the deathrate in any year must be multiplied by the factor 1.0615. The method pursued by the Registrar-General is as follows:-The mean annual death-rate for each sex, at each of the 12 age-periods, in England and Wales in 1871-80, is applied to the population of each of the 28 towns, with age and sex distribution as shown at the last census (1881). The result is a number called the standard rate, which varies in every town according to the age and sex distribution of the population of the town. The mean annual death-rate of England and Wales from 1871-80 (21-27) is then divided by this standard, and a factor is obtained for each town by which the recorded death-rate of any year must be multiplied. The factor exceeds unity in 26 towns, and is less than unity for two towns only out of the 28 (Annual Summary for 1883). It is not necessary to fractionate up the routine statistics of a district into so many divisions as represented in the foregoing table. I am content with regard to the statistics of my own district with five groups of ages. The following, for instance, is a table of rates at different ages for St. Marylebone during 1886; the natural values taken from the English life table being added for comparison. These numbers are obtained in a similar manner to the deathrates of the whole population already detailed at p. 14. The population at the groups of ages dealt with are extracted from the census returns; the deaths at that particular age-period collected from such a table as at p. 7, x 1,000, and divided by the population for that age. If the calculation is made for any fraction of a year, the rules given at p. 14 equally apply. For example, the deaths for the C TABLE IV. COMPARING THE DEATH-RATES FOR 1886 AT VARIOUS AGES, WITH DEATHRATES AT THE SAME AGE GIVEN IN THE ENGLISH LIFE TABLE. whole district between the ages of 20 and 40 were 395, the calcu lated population at those ages was 57,746, hence 395 × 1,000 = 6.8. In the intervals between the census the population at any age in increasing or decreasing populations must be calculated. For example, a population in 1881 of 154,910 contained 15,900 under 5 years of age; in 1886 the same population was presumed from calculation to be 156,290: then by an ordinary rule of three sum 15,900 × 156,290 16,035 population under 5 years in 1886, and so 154,910 = on for the remaining groups. (10) Zymotic Death-Rate. What is called the zymotic death-rate, is the rate of mortality per 1,000 of the population from the principal zymotic diseases-that is, small-pox, measles, scarlet fever, diphtheria, whooping cough, erysipelas, typhoid, typhus, and other forms of fever and diarrhoea. The calculation is precisely the same as that of an ordinary death-rate. For instance, in a population of 156,000 there died 123 from zymotic 123 × 1,000 maladies; required the zymotic rate : 156,000 = 0.78. = (11) Proportion of Deaths from certain Classes of Disease to the Total Deaths. This is a very frequent method of tabulating deaths, and in sub-districts in which the age-distribution is fairly equal, affords a good basis of comparison. The calculation is simple; the deaths from any class are multiplied by 1,000, and divided by the total deaths. The annexed table is an example of the classes usually selected. Taking the first column, to show its construction, the total deaths were 3,087, the 381 × 1,000 zymotic deaths 381, then figures in column 1. 3,087 = 123, which are the first The deaths from pulmonary complaints were 763, then 763 × 1,000 3,087 = = 247, which are the second figures in column 1, and so on with the other numbers. TABLE V. GIVING THE COMPARATIVE MORTALITY OF THE SIX REGISTRATION DISTRICTS PROPORTION TO A THOUSAND 1, includes Smallpox, Measles, Scarlet Fever, Diphtheria, Whooping Cough, Erysipelas, Croup, Fever, and Diarrhoea. 3, includes Phthisis, Scrofula, Rickets, and Tabes. 4, includes Marasmus, Atrophy, Debility, want of Breast Milk, and Premature Birth. 5, includes Hydrocephalus, Infantile Meningitis, Convulsions, and Teething. (12) Proportional Distribution of Deaths. In many instances it is impossible to locate the deaths which occur in workhouses and similar institutions, no exact address. being discoverable, and in these cases in getting out the death rates of sub-districts it is necessary to distribute the deaths according to the population. As this necessitates each time much calculation, it is more convenient to draw out once for all a table, the first line of which gives a factor obtained by dividing the population of the sub-district by the total population, in the second line this factor is multiplied by 2, in the third line by 3, and so on, up to 9. An example of this kind of table will make the system clear. In the author's district there are the following population groups: and the proportional table has been constructed by dividing each sub-district by the total population to give the first factor; e.g., by dividing the population of All Souls by the total population, 26,759 = 0.17, which, multiplied by 1, 2, 3, &c., gives the numbers 156.290 in the first column of the table; in the second a similar process has been adopted for Cavendish Square, thus the population of Cavendish Square, divided by the total population of the district gives the factor 09, and the same principle has been adopted with the other columns. TABLE VI. TO FACILITATE THE DISTRIBUTION OF DEATHS OF PERSONS WHOSE EXACT ADDRESS IS NOT KNOWN. The table is used in the following manner. Supposing there are 124 deaths to be distributed between the six sub-districts in proportion to their population; the number for All Souls for 100 deaths will of course be 17 (obtained from the first column by removing the decimal point), 20 will be 34, and for 4 the number will be 0.68. = For Cavendish Square the numbers will be 9 + 1·8 + 0·36 = 11·16; for the Rectory the numbers will be 17 +34 +0.68 21.08; for St. Mary the numbers will be 14 + 2·8 +0·56 = 17-36; the numbers for Christ Church will be 22+ 44+088 27 28; the numbers for St. John will be 21+ 42+084-26-04; and adding these numbers together they will be found to exactly make 124. E.g., All Souls Cavendish Square Rectory St. Mary St. John. = 21.08 11.16 21.08 17.36 27.28 26.04 124.00 and by adding the numbers to the deaths of the sub-districts, 124 will have been divided up proportional to the population. |