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'''John GRAUNT'''

b.  24 April 1620 - d. 18 April 1674

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'''Summary.''' Arguably the Father of Modern Statistics, Graunt produced
the first life table and, together with William Petty, founded the
English School of "Political Arithmetic".

John Graunt was born in London, the eldest child of
Henry and Mary Graunt. His father was a draper who had moved to London
from Hampshire. Graunt served an apprenticeship and eventually succeeded
to his fathers drapery business, becoming quite prosperous.
He was made a Freeman of the Drapers'
Company at age 21, and eventually rose to the important position
of Warden of the Company which he held in 1671-1672. 
Graunt held various civic offices at the ward level and
ultimately on the common council. He was a captain in the (military)
band, and a major in his last years (1671-1674). He died on 18 April
1674 at age 53.

Graunt lived in a period of great intellectual activity. It was a
period which cradled modern science. The Royal Society of London, which
played a seminal role in this, was 
founded in 1660. The old learning, with its appeal to authority, was
being replaced by enquiry and experiment.

In 1662 Graunt published his famous ''Natural and Political
Observations on the London Bills of Mortality''. This was the first
treatise on vital statistics, and shows the earliest attempt to
apply theory, if only "shop arithmetic", to real statistical problems.
Later, his friend Sir William Petty (1623-1687) used similar methods 
on Irish data (principally in "The Political Anatomy of Ireland''
(1672, published 1691) and ''Observations upon the Dublin Bills
of Mortality'' (1681)).
The two men, between them, founded the English School of what
was called "Political Arithmetic". Graunt has been assessed by [[Pearson, Karl|Karl Pearson]] as the Father of Modern Statistics.

Graunt explained in the Preface to "Observations'' how he had become
interested in the ''Bills of Mortality'', weekly reports whose
publication had begun in 1592. These had been a subject of
curiosity but he sought to distinguish between impression and fact
and found much underlying regularity in the data. He implicitly
accepted the stability of statistical ratios, such as the
(number of burials/population), and if the ratios were not stable he
sought reasons. Thus, when he made what was the first attempt at a
life table, he based his results on the twenty years 1629-1636 and
1647-1658 which were relatively less effected by plague \footnote
{The Great Plague occurred in London in 1665.}.

The basis on which Graunt made his calculations is not evident,
although he may have used a geometric series. Amongst the calculations
is an estimate of the size of an army which could be raised in London
based on the assumption that there are 107 males for each 100 females.
Graunt seems have been the first to make such an observation about
the sex ratio. He deduced that 34\% of the male population would be 
aged between 16 and 56. Typical of other calculations are that of
100 persons born, 36 die before age 6 and 7 survive to age 70.

Graunt's first crude life table led on to the mathematical work
of Edmund Halley (1656-1742) and thence to the foundations of
actuarial science. He had foreseen what we needed, namely the following
of a given group from birth to death. As it was, he did not have the 
ages of individuals at death, and his data was effected by migration
into the city of London.

The ''Observations'' were well received. On 5 February 1662 50
copies of the book were presented to the Royal Society. A Committee
was appointed to examine the book and reported favourably. King Charles
II was also impressed and recommended Graunt to the Society, and
on 26 February 1662, only a month after publication of the book,
Graunt was elected to the Society. In November 1664 he was elected
to the Council of the Society and he was a regular participant in
Council meetings until April 1666.

Late in his life, Graunt 
descended into poverty. This started off with the destruction 
of his house in the Great Fire of London in September 1666. But a
major cause was that he ceased his trade and all public offices,
apparently on religious grounds, after his conversion to Roman Catholicism. 
At the
time this was a controversial and unpopular step.

There were various further editions of ''Observations'' - a second
edition in 1662 and a third, much enlarged, and fourth in 1665. A fifth 
edition
appeared in 1676, two years after Graunt's death, apparently overseen 
by Petty. This contained a very few
"further observations".

It is worth noting that Bills of Mortality began to be published
in Paris just before 1670, apparently in response to the
appearance and evident value of Graunt's "Observations''. Indeed,
Graunt's work led on rather naturally to the universal registration
of births, marriages, and causes of death for purposes of the State.

It has sometimes been suggested that Petty was the author of
''Observations'' and, indeed, he made some claims to this effect after
Graunt's death. But on balance the suggestion does not seem well
founded. A careful assessment has been given by Karl Pearson 
in Pearson (1978, Chapter II). It should be noted, in particular, 
that Petty was a
member (chair) of the Royal Society Committee which considered
''Observations'' after its receipt from Graunt in 1662 and
reported positively prior to his election to the Society.


====References====
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|valign="top"|{{Ref|1}}||valign="top"|   Pearson, E.S. (Ed.) (1978). ''The History of Statistics in the 17th &amp; 18th Centuries against the changing background of intellectual, scientific and religious thought. Lectures by Karl Pearson given at University College London during academic sessions 1921-1933'', Griffin, London (especially Chapter II). 
|-
|valign="top"|{{Ref|2}}||valign="top"|   Sutherland, I. (1963). John Graunt: a tercentenary tribute, ''Journal of the Royal Statistical Society Series A'', '''126''', 537-556.
|-
|}
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Reprinted with permission from
Christopher Charles Heyde and Eugene William Seneta (Editors),
Statisticians of the Centuries, Springer-Verlag Inc., New York, USA.

[[Category:Statprob]]
[[Category:Biographical]]