Estimates of New Zealand Maori Vital Rates from the Mid-Nineteenth Century to World War I

Population Investigation Committee

Estimates of New Zealand Maori Vital Rates from the Mid-Nineteenth Century to World WarIAuthor(s): D. I. PoolSource: Population Studies, Vol. 27, No. 1 (Mar., 1973), pp. 117-125Published by: Taylor & Francis, Ltd. on behalf of the Population Investigation CommitteeStable URL: http://www.jstor.org/stable/2173457 .

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Estimates of New Zealand Maori Vital Rates from the Mid-Nineteenth Century to World War I

D. I. POOL

I. SOUTH PACIFIC HISTORICAL DEMOGRAPHY

For a number of indigenous South Pacific populations it is possible to write histories based on mission and administrative records, which run back well into the early nineteenth century.' As the land areas of the South Pacific are restricted in size, it is often the case that one report is of more general applicability than would be true for larger populations. At the same time, the islands are isolated and were subject to the sudden introduction of alien diseases, so that, from an epidemio- logical standpoint, historical research has a wider interest than might otherwise be the case. Again, to-day they are high-growth populations, but very few of the world's other contemporary high- growth populations have records covering more than the post-World War II period. Finally, the South Pacific populations are often 'closed', which, from an analytical standpoint is highly desirable.

Recently, some South Pacific populations appear to have undergone rapid declines in mortality after decades of very high death rates. The available evidence suggests that mortality levels increased after contact with Europeans reaching peaks in the nineteenth century, particularly during epidemics, then declined gradually until the period of accelerated decrease after World War II. Probably the birth rate was, under normal circumstances, reasonably high.

Such a case, while logically attractive, is difficult to support with quantitative evidence. For example, in New Zealand2 compulsory vital registration for the indigenous, 'closed' Maori population was introduced in I9I3, but until the mid-I930's the standard of registration was very poor indeed. However, for Maoris as for other indigenous South Pacific islanders, vital rates can sometimes be calculated directly from data collected in particular years for restricted regions by missionaries, administrators and others.

In Table I a range of rates of this type are presented for New Zealand Maoris. In general, the death rates given there support the comments made earlier about levels of nineteenth-century mortality. But the case supporting high fertility is not as strong, because birth rates are in the middle range going as low as 30 per i,ooo. This may be the result of the depletion of certain cohorts, an aftermath of the epidemics and wars between I 8oo and I 870, the result of the dissolution of unions during periods of high mortality, or of poor data (birth was culturally less significant than death, which was followed by a 'tangi' or wake, thus making births less noteworthy and birth data more difficult to collect) so that fertility may have been higher than these rates suggest. Regardless of which of these explanations is true, it is certain that conclusions based on these rates cannot be accepted with complete confidence. Thus, it is necessary to attempt to obtain vital rates by means of indirect estimates.

1 See Norma McArthur, Island Populations of the Pacific (Canberra, I968) for Fiji, Tonga, Samoa, Cook Islands and French Polynesia.

2 I exclude its former and present island territories: Cook Islands, Westem Samoa, Niue and Tokelau Islands.

I I7



II8 D. I. POOL

TABLE i. Vital rates calculated directly from available data: New Zealand regions and localities, nineteenth century

CRUDE DEATH RATES

Rate Period Method of estimation Source of data Region Comments or calculation

45.3 I844-58 The data give a ratio Mission registers New Zealand extra- Affected by the of i death to 22-I4 (I844) compared by polated from Wai- measles epidemic people for the Wai- Fenton with data kato. Fenton directed of I854. Thus, a kato. This ratio was collected by him the entire census and 'high normal' rate. extrapolated to Fen- personally (I857-58) also enumerated ton's census popula- checking for migra- Waikato region him- tion for New Zea- tion since I844. self, the most tho- land as a whole. rough enumerationof

the census.

57-83 I854 Applying various Official dispatches. New Zealand. A measles epidemic estimates of the Accounts written by death rate. number of deaths to Swainson and two 'reasonable' Thompson. estimates of population size made by contemporary observers.

32@2 I869-74 Average annual deaths McKay, census re- Certain South Island Very small popula- for the period ap- port. District com- provinces. tion. Probably an plied to I874 census missioners'reports. area with 'lower' dates. mortality than

North Island regions at this time.

38-50 i873-78 Estimated from com- Census report. Dis- Raglan. Claimed to relate to ments of Bush that trict commissioner's non-epidemic mor- before I878 the ratio report. tality, but the I875 of deaths to births measles epidemic was I0: 8, and as- fell in this period. suming the crude birth rate was 30-40.

6o-8o I878 Comment of Bush Same. Raglan. Whooping cough that deaths doubled epidemic. births. Same crude birth rate as for rate above.

73 I878-8I Average annual deaths Same. Canterbury, South Whooping cough applied to census Island. epidemic. population.

30-8 I878-79 Deaths applied to Same. Mangonui. Perhaps the most census data. There settled North Is- are certain difficulties land region. Non- with the data on epidemic mortality. population at risk.



ESTIMATES OF NEW ZEALAND MAORI VITAL RATES II9

TABLE I (continued)

INFANT DEATH RATE

Method of estimation Rate Period or calculation Source of data Region Comments

4IO I874 Death and births after Census report. Raglan. Probably far too allowance is made high. Moreover, for childhood deaths based on very termed 'infants'. small numbers.

Perhaps 200-300 would be more reasonable infant mortality rates.

CRUDE BIRTH RATES

29*8 I845-58 From Fenton's data Fenton (see above). Waikato extrapolated Cohorts reaching (see above). to New Zealand. reproductive ages

during these periods had been successively de- pleted by wars and epidemics.

32*4 I874 Births related to cen- McKay (see above). Certain South Island sus data. provinces.

35 8 I878-79 Same. Census (see above). Mangonui.

SOURCE: D. I. Pool, 'The Maori Population of New Zealand', unpublished Ph.D. Thesis (Canberra, I964), chap. 4.

2. THE INDIRECT ESTIMATION OF VITAL RATES

To obtain estimated vital rates for the population as a whole one must use enumeration data as a base. There are many methods available to carry out such an analysis, but the minimum requirement is the availability of at least one and preferably two censuses with a published breakdown by quinquennial age groups. Moreover, the populations under analysis should, in principle, be 'closed' and 'stable'; some methods are satisfactory only if the population is quasi-stable. In the nineteenth and early twentieth centuries there were such rapid and major fluctuations in the mortality of New Zealand Maoris that one pre-condition for quasi-stable structure, namely that 'mortality has changed only slightly and gradually during the past generation'3 clearly did not hold. To complicate this even further, epidemics of diseases against which one attack gave life-long immunity, were so distributed that peculiar patterns of age-specific immunity (and thus mortality during a subsequent epidemic) developed: for example, the dates of occurrence and implied patterns of immunity for the early epidemics of measles are given in Table 2.

3 United Nations (A. J. Coale and P. Demeny): Manual IV: Methods of Estimating Basic Demographic Measures from Incomplete Data (New York, I967), p. I2.



120 D. I. POOL

TABLE 2. Nation-wide measles epidemics

Age groups Age groups immune (i.e. persons who Date of occurrence with heavy in a closed population, had survived

mortality an earlier nation-wide epidemic)

Before i854 there was only one recorded epidemic occurring in a restricted area in the South Island.

I854 All ages* None I875 0-2I 2I+

i882 o-7 7+ I885 0-3 3+

From i885 these epidemics became regular and the disease a 'childhood disorder'.

* The fact that this epidemic attacked all age groups was specifically mentioned by observers who were surprised, often attributing the cause to 'inferior constitutions', e.g. see John Miller, Early Victorian New Zealand: A Study of Racial Tension and Social Attitudes, z839-52 (London), p. io6. Quoting Rev. Hadfield.

SOURCE: As for Table i. Based on content analysis of official dispatches to Colonial Office; British Parliamentary Papers; Appendices to the Journal of the House of Representatives (N. Z.; Mission records; journals of settlers, officials, missionaries, travellers, etc.

For a 'closed' population it is not necessary to assume that the structure is quasi-stable if one uses for estimates the survivorship of cohorts between censuses as a basis. However, there is the problem of intercensal differences in the quality of enumeration for the same cohort. It thus becomes impossible to determine whether the survival ratios so derived are due to intercensal changes in the quality of cohort enumeration, or show genuine substantive trends. Graduation of five-year age groups merely confuses the issue, particularly when one is dealing with small4 populations exposed to high levels of age-specific epidemic mortality.

In part, this problem can now be overcome by methods derived from the Africa project of Princeton's Office of Population Research. By cumulation, the effects of age misreporting are reduced. At the same time the development by Coale and Demeny of four 'families' of model life tables permits flexibility when fitting observed data to model populations. However, this method has some inherent weaknesses,5 so that although it will be employed in this paper, the results obtained will be compared with alternative, 'independent' estimates in order to assess their validity. The major computational problem is to select the correct family of Tables (in this case 'West' made the best fit) but even more basic than this was the quality of the available census data.

3. EARLY MAORI CENSUSES6 For the Maori population of New Zealand there were nation-wide censuses containing a

published age breakdown for the period before World War I. A full 'enumeration' of Maoris was first taken by Fenton in I857-58, and censuses were then held fairly regularly, but until the i88o's contained very broad age breakdowns only. Moreover, they failed to meet reasonable enumeration

4 The Maoris numbered 43,927 (i886); 42,II3 (I896); 45,330 (I90I); 52,723 (I9II). 5 United Nations (A. J. Coale and P. Demeny): Manual IV: Methods of Estimating Basic Demographic Measures

from Incomplete Data (New York, I967), pp. 8-I2. 6 A condensation of D. I. Pool, 'The Maori Population of New Zealand', unpublished Ph.D. Thesis (Canberra,

I964), chapters 2 and 3.



ESTIMATES OF NEW ZEALAND MAORI VITAL RATES I2I

standards: the enumeration was often prolonged; estimates rather than counts were made for certain groups; while the allocation of 'half-castes' to the Maori (i.e., 'half or more Maori-blood') or European (i.e. 'half or less Maori blood') censuses according to the individual enumerator's assessment of their mode of living was a particularly uncertain procedure. There were, as we implied, considerable regional differences in quality, although some account of these differences may be obtained from the detailed district census reports made by magistrates and district commissioners.

From the Census of I886 onward, quinquennial age-groups (a-i9) and decennial age-groups (20+) were published, and thus intercensal survival rates can be calculated. Although censuses were held every five years the fact that ages are given in ten-year groups for persons aged 20 and over restricts the analysis to ten-year spans. Thus, the first available decennial span is used as an example (i886-96). i896-i906 cannot be used because detailed ages were not published for I906. From I9II on ages were published in quinquennial groups, but the I9I6 Census was noted to be poor both in terms of coverage and age-reporting, while by 1921 the 'half-caste' rule mentioned above was becoming unworkable. From 1926 onwards census procedures for Maoris and non-Maoris became identical and a more workable definition of Maori was used. To make viable estimates of early vital rates one is restricted to the intercensal periods I886-96 and I9OI-II.

4. RESULTS: I886-I9II

The estimated vital rates and levels of life expectation7 are given in Table 3 for Maori females. The period I886-96 included the pandemic of influenza when mortality is known to have been

extremely high. However, the I896 Census was relatively less satisfactory, in terms of the number of persons enumerated (but not of age reporting), than that of i886,8 and thus, part of the overall percentage decrease may have been due to this. It is possible that estimated life expectation at birth is too low, that the crude death rate is too high and the rate of decrease too great. Suggested alternatives are given in brackets.

The figures for I9OI-II seem entirely plausible, with the birth rate relatively close to independent estimates, assuming quasi-stability and including the application of the I964 age-specific rates to the age-distribution for I9OI-I i (Table 3).9 A further independent cross-check can be made by comparing recorded child-woman ratios for I9OI with 'expected' ratios which are given in Table 4.

7See United Nations, Manual IV, op. cit., and A. J. Coale and P. Demeny, Regional Model Life-Tables and Stable Populations (Princeton, N.J., I966). For the intercensal periods I886-96, I9OI-II, there is no way of obtaining data on age o and on quinquennial age-groups 20-24, , 65-69, 70+. Therefore:

(a) Survivorship was calculated as follows: p t+10 p t+10 pt+10

10+ 20+ 30+ pt ' pt ' pt etc.

0+ 10+ 20+

(b) For age-groups 20-29, 30-39, ... , 6o-69, 1OD. were computed by applying the average of the two quinquennial age-specific mortality rates to the 1oP,. A small loss of accuracy would result from this procedure.

(c) To calculate Do and D1l4 it was necessary to obtain PO and P1l4. This was done after the relevant model

life-table had been selected by using the ratio: L as a separation factor.

8 D. I. Pool, op. cit., chapter 3. 9 This has limited validity. In I956 the stable and enumerated populations were very close except for differences

explicable in terms of the post-World War II declines in infant morality. This close 'fit' implies that similar levels of fertility had occurred since I900.



122 D. I. POOL

TABLE 3. Estimated levels of life expectation at birth, and vital rates I886-96, and I90I-I I, Maori females

I886-96 I9OI-II

eoo 20-0 (22-5-25-0) 32,5-35,0 Annual rate of growth (r) -0-005 (-0-003) +O-OI5 Crude death rate oo48 (0 045) 0o028 Crude birth rate 0-043 (0o042) 0?043 Alternative estimates of the crude birth rate for I9OI-II based:

(i) on age-specific fertility rates (I964) 0-042

(ii) on the G.F.R. for I96I 0-048

(iii) on fitting certain parameters* to 'West' stable model populations 0-049

Altemative estimate of the crude birth rate for I886-96 based: on fitting of certain parameterst to 'West' stable model populations o0o44

* If r=o-oi6; if CO14=0o42; and if the population is quasi-stable, then e00(f) 30, and the crude birth rate exceeds 0o049. Parameters for r and Cx from published data.

t If r =-0003; if Cx = 0-37; and if the population is quasi-stable, then e00(f) 20, and the crude birth rate exceeds o o44. Parameters for r and Cx from published data.

TABLE 4. Expected child-woman ratios, I9OI

(Ratios calculated from the following levels of crude birth rates and life-expectation)

Level of life expectation at birth, in years (U.N. Model Life Tables) Crude birth

22-5 25-0 27-5 300 32-5 35-0 37-5 400

0-025 364 379 392 404 4I5 425 435 445 0-030 436 454 470 484 497 5IO 522 533 0-035 524 457 563 582 600 614 628 64I 0.040 578 607 628 647 666 680 699 7II

0-045 657 683 704 729 747 766 784 798 0o050 730 76I 786 8ii 832 85I 874 89I

The 'expected' ratios were calculated as follows: Births were estimated for the period I896-I9oI.10 Survival ratios calculated from U.N. model life-tables were employed to age these estimated births to ages 0-4. 'Expected' child-woman ratios could then be calculated by taking the estimated survivors aged 0-4 as the numerator, and the enumerated females aged I5-49 (1901 Census) as the denominator.

A wide variety of combination of birth rates and mortality levels were experimented with, from a birth rate of 0 025 to one of 0 050; from a life expectation of 22-5 years at birth to 40 years. These 'expected' ratios were then compared with the I9OI census ratio, which was 567 per I,OOO women aged 15-49 years.

10 Under normal circumstances this would have been calculated as follows:

B1896-1901 = 5 (b x P1896 + P10ol) 2

where b is the crude birth rate. However, only P1901 was used because of the problems posed by epidemics in the early I890's and underenumeration in certain regions in I896.



ESTIMATES OF NEW ZEALAND MAORI VITAL RATES 123

The 'expected' ratios are presented in Table 4. Those closest to 567 had been calculated from birth rates of 0o03o, o0o35 and o0o40. As was shown in Table i, birth rates as high as this have been estimated for a few regions for periods earlier than i896-i9oi.

So far no allowance has been made for the accuracy of the I 90I data from which the ratio of 567 was calculated. Yet, it can be shown thatthe reporting of ages -4 in I9OI was most unsatisfactory. 5,399 persons aged -4 were enumerated in I9OI, but by I9I1 this cohort hadgrown by 569 persons and numbered 5,968. If it is assumed that the enumeration in I91 I was correct, which is unlikely, the difference of 569 implies a level of underenumeration in excess of io% in I9OI, and by taking some account of intercensal mortality it can be shown that the level might even have been as high as 29%.11 There may also have been underenumeration at ages I5-49 in I9OI, but an inspection of decennial age groups revealed that underenumeration at ages o-4 was considerably in excess of that at ages io-i9, and was also probably rather higher than at ages 20-49. If this excess is assumed to be between i5 and 25 %12 the I9OI child-woman ratio is increased to the range 652 to 709, which compares favourably with 'expected' ratios calculated from birth rates of 0-035 to 0-045 and from levels of life expectation at birth of 3o-40 years. If an adjustment for an excess of 29% is made a ratio of 73I is obtained.13

The allowance made here for underenumeration is not unreasonable. This is evidenced by the fact that a similar range of child-woman ratios was recorded in I9OI for those regions which had a long history of relatively reliable enumeration stretching back to Fenton's census of I857-58. They were: Northern North Auckland (753); Southern North Auckland (63I); Manawatu- Horowhenua (64I); and the South Island (720).

5. INDIRECT EVIDENCE ON THE POSSIBLE LEVELS OF VITAL RATES PRIOR TO i886 So far the evidence points to high mortality and fertility from i886. Table i also shows high

death rates before i886, but birth rates as low as 0029. Are such rates feasible ? Some very crude indirect evidence which is available would suggest that they are not. The

data are: (i) the proportion of the population variously enumerated as aged o-14 years, 0-13 years, or as 'non-adults', and (ii) the intercensal rate of growth. Often in censuses the age-group o-I4 years is poorly enumerated, so that the estimated birth rate is probably too low. On the other hand, one must assume that the population was quasi-stable, which is problematic given the strongly destabilizing effect of epidemic mortality. There is also, it may be noted, a rather peculiar destabilizing factor operating. With the occurrence of a first epidemic of a disease with a pattern of life- long immunity derived from exposure on one occasion, the size of the population will be reduced dramatically, but more or less proportionately at all ages. Thus the age distribution remains, as it were, 'stable', yet the population has been destabilized. This would be true for the period 184o-58, certainly for measles and possibly for whooping cough (there may have been an epidemic about 1845). By contrast, mortality would have been specific to certain ages during the I875 measles epidemic (see Table 2) and the influenza pandemic of about I851 (as influenza

Estimated as follows:

Expected (Ex) Pl9?l -Observed (Ob.) P 'go

(Ob. P 1j01 where

(Ex) Po9?4=_Plo9l4 x 5LIo 0-X4 0-` 10- 14 r L10 Survivor years were taken from 'West' 7 of the Coale-Demeny tables.

12 This assumes that the underenumeration at ages IO-I4 (I9II) was not as high proportionately as that at ages 15-49 (I90I).

13 This assumes that the underenumeration at ages IO-I4 (I9II) was at the same level as that at ages I5-49 (I90I).



124 D. I. POOL is always age-specific), and possibly in I876-77 for whooping cough (depending on whether or not there had been an epidemic in I 845). Finally, such epidemics have a further destabilizing effect on fertility because widowhood/widowerhood affects mating patterns. Perhaps i6% of unions could have been so dissolved in the I854 measles epidemic, as against 7/i6th in the catas- trophic I 875 measles epidemic in Fiji.'4 In sum, what follows is subject to considerable error.

Nevertheless, one cannot but be impressed by the fact that, although mortality was extremely high and in the face of frequent reports about the 'absence of children' in Maori communities, the proportion of the population under I5 enumerated remained high. The lowest recorded proportion was about 26% in the I840's for various mission 'censuses', but typically the proportion was in the range 33-37 %. For such a proportion (say 35 %) to be achieved from a birth rate as low as 0.029, female life expectation at birth on would have had to have been at the level of 50-55 years (a level not reached until well after World War II), and r at least OOI5. Even the assumption of a birth rate as low as o0035 would imply an e00(f) of 45 years. In fact, even taking 'West' level i where e00(f) = 2o0o and r = Ooio implies that the birth rate must have been at least 0-038. But for several of these periods r -ooi6 to -00I4 so that for these periods the following vital rates might have occurred:

eoo <20 crude birth rate > oo38

crude death rate > 0048 If the population had been quasi-stable and if the life expectation at birth had been less than 20 years, say (i) I50 years, and (2) 7-5 years, then the following death and birth rates might have occurred:

(I) True death rate d = o-o67

Implied birth rate = d - r #-.05I

I (2) True death rate = .0*057

Implied birth rate . 0-04I The death rates suggested here are higher than those calculated from fragmentary direct

evidence relating to 'normal' years. But every census, from which r and C. are drawn, was preceded by years during which epidemic mortality had been so high that officials and others reported this fact as evidence of the 'racial inferiority' of Maoris. It is possible that the 'r's' used here (until I 896 these were negative) show too rapid a decline, although logic would suggest that accuracy of enumeration should have improved and thus that poor enumeration would result in Pt-n being less than Pt. I857-58 was the first nation-wide census, but the r used here for the period was that recorded in Waikato where Fenton, the census enumerator (and a man who had long worked in the region), compared his census results with mission data which permitted allowance to be made for migration. Estimates calculated by comparing, estimates of national population size usually considered among the more 'reliable' and certainly in the modal range, with Fenton's census give a much higher rate of decrease. But even accepting e00(f) = I5, true death rate= o-o67 and r = -0020, the birth rate would still be high.

6. CONCLUSION

These various estimates support the contention that the birth rate at the turn of the century was high rather than low; i.e. somewhere about and probably above, o0o40. It can also be argued

14 Cf. Norma McArthur, Introducing Population Statistics (Melbourne, I96I), p. I7-I9.



ESTIMATES OF NEW ZEALAND MAORI VITAL RATES 125

that at this time life expectation was very low, somewhere between 32-5 and 37-5 years at birth, but had reached even lower levels during epidemics, perhaps lower than 20-022-5 years, as was estimated for I886-96.

This means that fertility, as measured by estimated crude birth rates, was not low at the turn of the century. Even when there was an actual decrease of population (I886-96) the crude birth rate exceeded 0-040; the decrease being engendered by very high mortality. Even by taking the analysis back further to the I840's and i85o's the evidence strongly suggests that birth rates were high. This view runs counter to the arguments of polemicists of the period, of academics in the ig20's and even of Firth in I95715 that the birth rate was 'low' or that their 'numbers decreased' as a result of the psychological depression of the Maoris caused by contact with Europeans. These writers were undoubtedly confusing birth rates with replacement rates. In terms of replacement the evidence points very clearly to extremely low levels of survivorship resulting from epidemic diseases,16 warfare and endemic disorders; there is no need to search for psychological causes in the face of very strong evidence, albeit qualitative and/or indirectly estimated from r and C., relating to mortality.

5- Raymond Firth, Economics of the New Zealand Maori (Wellington, I957), p. 456. 16 High Maori incidence, case-fatality and age-specific death rates in one epidemic are discussed in D. I. Pool,

'The Effect of the I9I8 Pandemic of Influenza on the Maori Population of New Zealand', Bulletin of the American Society for the History of Medicine (forthcoming).



Documents

Estimates of New Zealand Maori Vital Rates from the Mid-Nineteenth Century to World War I