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2ND SEPTEMBER 1891, Nos. 2117, 2118 L., LOCAL AND MUNICIPAL.
From Surgeon-Major W. G. KING, M.B., on Special Duty, Bangalore, to the
Chief Secretary to Government (through the Secretary to the Surgeon-
General with the Government of Madras), dated Bangalore, 18th August
1891, No. 431.
With reference to my letter No. 417, dated 4th August 1891, addressed to you
through the Sanitary Commissioner, I have the honour to now forward statistical proof
of the correctness of my assertion that the serious fall in the percentage of success
mentioned in the report on vaccination for 1890-91 of 1.4 per cent, upon the total
vaccinated, as compared with that of the previous year, is not due, as therein asserted,
to the use of lanoline vaccine. My claim in the letter mentioned was that the most
that could be said was that a decrease of either .4 or .5 per cent. had been so brought
about, whilst it was probable that the further loss of from 1 per cent. or .9 per cent.
was due to the large increase of operations, which must naturally yield a lower percen-
tage of success, namely, under re-vaccination. Remembering, however, the proverbial
saying that " statistics can be made to prove anything," I thought it advisable to ask
the Inspector of Vaccination to kindly supply me with the full statistics from which
he had drawn his conclusions (see attached memorandum).
2. From a perusal of this memorandum, it is at once evident that the real
difference between the percentage of success gained in 1889-90 and 1890-91 is not
that between 95.9 and 94.5, but between 96.99 and 96.50, the loss per cent. by the
inclusion of cases performed with lanoline vaccine being, therefore, not 1.4 per
cent. but only .49 per cent. This curious difference of results, I find, is brought about
by the Inspector of Vaccination having used the absolutely unsuitable method hitherto
employed in the office of the Sanitary Commissioner as to reckoning the percentages
of success. It has been the custom in that office to class all " unknown " cases with
the unsuccessful. This mode, which I believe has met with the approval of Govern-
ment ever since the Vaccination department existed, is good enough for showing how
many cases of successful vaccination are known to have been inspected of the total
vaccinated, and it is probable that for this purpose alone this peculiar method of sta-
tistical investigation has been originally ordered. But, when it is used to demonstrate
that the employment of a special form of lymph caused a loss of percentage of success,
it is open to serious objection, and is in fact, useless. Employed thus, ceteris paribus,
the only effect would be to exhibit the ratio of " unknown," in each class respectively,
inextricably mixed with the question of percentage of successful vaccination. It will
be found that the number of "unknown " cases under the lanoline vaccine system is
as 100 to 31.93 by all other methods—a result due to the fact that the vaccinators
at first worked in groups, and operated upon all and sundry they met in villages
or on roads—inhabitants and travellers from distant parts alike—leading to its being
impossible to subsequently inspect a certain number of cases.
* See note by the Inspector of Vaccination
quoted in attached memorandum.
3. As an illustration of the absurd effects of trusting to this mode of calculation,
I would point to the fact that my own percentage of success, including perforce an
unascertained number of re-vaccinations,*
amounting to 90 per cent. would, if
subjected to the Inspector of Vaccination's
method of calculation, become 85.2 per
cent.; whilst if the same proportion of " unknown " was added to his total cases—of
course, retaining the relative ratio of successful and unsuccessful cases—the rate of
success would fall not to 94.5 per cent., as shown by him, but to 91.4 per cent., or,
excluding lanoline vaccine cases, to 92.05 per cent.
4. I regret to have to trouble Government on a matter that may be considered
by them trivial; but, I respectfully ask them to remember that, after working for six
months to introduce the use of lanoline vaccine, it would argue the presence of a
peculiarly callous disposition, were I to permit a false deduction of the nature I have
explained to be circulated to various officers throughout India unnoticed by me. It
would, of course, have been expecting too much of the Inspector of Vaccination to
have anticipated that, whilst sparing space to call attention in a concise report to the
ow percentage of success obtained with " lanoline vaccine," he could also have spared