The Sun.
London, England, 1865-09-08 00:00:00

STATISTICS AND POLITICAL ECONOMY.

This section assembled in the Friends' Meeting-house,
and was presided over by Lord Stanley. Sir J. Bowring,
Professor Fawcett, M.P., and Lord Lyttelton were among
the principal persons present. After some purely formal
business,

Lord STANLEY delivered an address on the value and use
of statistics. lie said—ln opening the section of statistics
and political economy, I need not trouble you with more
than a few introductory remarks. It has been questioned
how far such subjects ought to form part of the business of
a strictly scientific association, and I don't think the ques-
tion unreasonable, for it must be admitted that while even
political economy itself, in its present state, is rather a col-
lection of practical maxims, stipported by reason and tested
by experience, than a science in the same sense as astro-
nony or optics are entitled to that name, the topics to which
the statistical method is applicable are infinitely various,
and have little in common, except this one characteristic,
that in every case we appeal either to the numerical tests
of accuracy, to figures, or else to fixed and recognised rules,
which are assumed to have the same kind of certainty as
prevails in physical science. How far that assumption
holds good in practice must depend on the judgment both
of those who read papers and of those who comment upon
them. The truth is, in my opinion, our functions here are
rather those of suggesting, an _stimulating than of origi-
nating thought. Discussion, no doubt, we shall have, and
in discussion new ideas are constantly generated, and new
lights thrown upon previously unfamiliar topics. But it
is not in crowded meetings, it is not in debating speeches
that any profound and original investigation can be carried
on. Meetings like ours answer two purposes apart from that
of social enjoyment. One of those is the diffusion, not the
origination, but the diffusion of ideas. Books and news-
papers and reviews, no doubt, are the main agents for doing
that work. Still it is, I think, indisputable that, as seeing
is proverbially more impressive than hearing, so what we
hear orally delivered makes upon us a stronger impression
than that which lies on a printed page, on which our at-
tention may or may not dwell. The other is the stimulus
given to inquiry by the mere fact of investigations of this
kind, or the result of them, being brought prominently and
conspicuously before the public. Men go home with their
heads full of subjects on which they perhaps never thought
seriously before. And since, as I believe, nothing once
known is ever really forgotten—since an idea which has
once found lodgment in the mind, though its presence there
may long have been barren, and though we ourselves may
be unconscious of it, will often spring up with life after a
long interval—it is difficult to determine what crop may
not grow, sooner or later, out of the seed thus cast about
apparently at random. (Hear, hear.) And now let me say a
word as to the right application of the statistical method.
To use figures rightly, assuming that they are accurate in
themselves, is not as easy a matter as it is apt to appear.
There are various fallacies into which unpractised statisti-
cians fall, one or two of which may be worth noting. One,
perhaps the commonist, arises from the use of too narrow
a basis for calculation. To explain my meaning : given a
certain class of men between certain ages, as soldiers, agri-
cultural labourers, artisans, and the like, the aggregate
length of life among 10,000, or even among 1,000, of those
will be practically a fixed quantity; you can determine it
beforehand. But the length of any single life is, of course,
uncertain ; and if so few as 10, 20, or even 100 lives be
taken, the element of chance, or what we call chance, is
not sufficiently excluded ; and a single exceptional case
affects the general result. Another error, less easy to
detect, arises from not taking into account all the
causes which affect the result. Thus, supposing that
the question is the effect produced by the reduction of
a tax in increasing the consumption of the article taxed, it
is a natural but a very obvious mistake to argue—post hoc
ergo propter hoc—to speak of that augmented consumption
as arising solely from the reduction of duty which preceded
it, ignoring other causes—such as general prosperity and
consequentaugmentation of the consumingpower, cheapen-
ing of means of transport, or lowering of the actual cost of
production by mechanical improvements, or otherwise, of
the article consumed. Or, to take an illustration from a
different class of subjects, suppose it is desired to ascertain
the average mortality of a certain class, that for this pur-
pose we take the mortality in that class during a certain
number of years, and that during one of those years an
epidemic of a destructive character has prevailed. You,
of course, strike out that year from the series as unduly af-
fecting the average. But if you stop there, your calcula-
tion is again vitiated, though in a different manner. For
it will almost always happen that an epidemic sweeps
away a larger proportion of unhealthy than of healthy
lives ; and so the years succeeding, their mortality having
been, so to speak, anticipated, are above the true average
in point of health, and do not form a fair basis for a per-
manent calculation. (Hear, hear.) Another variety of the
same error, identified in principle, is where effect andcause
are confounded. For instance, I have heard a sanitarist
argue, with great general truth, in favour of model lodg-
ings in towns, and support his argument by pointing out
the diminished ratio of mortality in them as compared with
the same class outside. No one could dispute the general
conclusion. But in fairness it should have been taken into
qualifying proposition, that model lodg-
i
putation for superior cleanliness and
ci
no
gnas! d ebrya t itohne,
ra s
rae
healthiness, attract not the average, but the best men of
the class in point, of regular and orderly habits, for whom
they are designed—that is, those whose chances of life
are the best, independent of the manner in which they
are lodged. Hence involuntary exaggeration arises, by
which a good cause can only suffer. (Hear, hear.) A
third source of error, perhaps less material, but still
worth notice, is that of confounding in one class facts
not identical. For instance, the average death rate in
England is easily ascertained ; but if you wish to apply that
practically to a particular place or class, you must not take
the figures as they stand. The death rate of towns is not
that of rural districts—the mortality of infants greatly ex-
ceeds that of adults ; the term of life is shorter in the la-
bouring than in the well-to-do class. Age, class, locality,
must be separately determined before you can arrive at an
even approximately accurate conclusion. The figures which
serve for all collectively, precisely because they do so servo,
are illusory if applied to any one of these in particular. I
mention such possible mistakes in order to show how utterly
wide of the truth is the idea that, to work by and with sta-
tistical calculation is a merely mechanical function needing
no ability beyond that of a careful clerk. They require
common sense and vigilance against errors, like every other
method of inquiry. Figures do not, indeed, deceive you ;
but if you put them to a use they were not meant for they
will let you deceive yourself. (Hear, hear, and a laugh.)
I suppose it is hardly necessary to remind you of the uses
of the statistical method as applied to national affairs. If a
man in private life finds his money going too fast and wants
to retrench, the first thing he does is to say, " I must keep
accounts." So individuals keep diaries of particular matters
in which they are interested, not trusting to vague recollec-
tion, but setting down their notes day by day. Everyper-
son of observant habits or engaged in any pursuit which
requires accuracy, is in some sense a statistician. And it is
hardly possible to overrate the value of figures, partly as
checking the universal tendency to exaggerate, not wilful,
but a kind ofn t
ere mentalsted
, artilplusiloyn, which operates whenever we
are as
giving definiteness and pre-
cision to ideas which would otherwise remain floating in our \
minds in a vague and therefore comparatively useless form.
For instance, to say generally that a given trade or deeply
i
employ-
ment—that of a grinder, or of asoldier in the Tropics—is
unhealthy, conveys a very faintimpression, and affects our
feelings but slightly. But yet it is in this way that the
average length of life in some occupations is shorter by 10
or 15 years than that of an ordinary labourer ; and it is only
by habitual calculation that the man himself, however igno-
rant or thoughtless he may be, is able clearly to realise
the sacrifice he is making in going into that business. So
with regard to questions of drainage, of ventilation, of food,
of the use or abuse of strong drinks, it is the statistical test
employed on a large scale which alone can be conclusive. I
say on a la
rge scale, for it is of the very essence of statistical
inquiry that by dealing with masses it eliminates individual
peculiarities. We reason back from the mass to the indi-
vidual ; the subject of the statistician, his typical or repre-
sentative man, is the average man of many thousands. We
are familiar with the effect on public health of the establish-
ment of sanitary statistics. Let me point out one or two
instances in which figures form part, and a very curious
part, of the doings of our national life. Take the Post-office
returns, showing increase of correspondence as compared
with the past, and the difference which exists in the amount
of letter writing between one part of the country and
another—say between the population of Irelandand that
of London. Take the Registrar-General's returns of mar-
riages, and note how the number of these relatively to the
population rises and falls as the material condition of the
masses is for the time better or worse. Take the annual
publications of the Customs and Excise departments.
Take our census abstracts of the occupations of the people;
take our criminal statistics—a comparatively new depart-
ment, and one probably still admitting of much im-
provement ; you may read in these collectively the social
and economical history of the age in which wo live, and
note everywhere the absence of mere chance. We speak
of chance— it is a word which we must use for convenience
sake—but we really mean by it not that the result
or the thing discussed is in itself uncertain, but
that some or all of the determining causes of such re-
sults are to us unknown. We Imply not the absence of a
law, but inevitable iguorancli 011 our part, of whet the law