Graphics Reference
In-Depth Information
the
cholera cases by hatching in red 'the districts in which the cholera had pre-
vailed.' In his report, he noted an association between the disease and living con-
ditions: 'how exceedingly the disease has prevailed in those parts of the town where
thereisadeficiency,otenanentirewantofsewage,drainageandpaving'(Baker,
,
p.
).Bakerdidnotindicatetheincidenceofdiseaseonhismap,norwasheequipped
to display rates of disease (in relation to population density),
and his knowledge of
possible causes, while definitely on the right track, was both weak and implicit (not
analysedgraphicallyorbyothermeans).Itislikelythatsome,perhapstenuous,causal
indicants or evidence were available to Baker, but he was unable to connect the dots
or see a geographically distributed outcome in relation to geographic factors in even
thesimplewaysthatGuerryhadtried.
At about the same time,
-
,the use ofgraphs began tobecome recognized
insomeo
cial circlesforeconomic andstate planning -wheretobuildrailroads and
canals? What is the distribution of imports and exports? his use of graphical meth-
ods is no better illustrated than in the works of Charles Joseph Minard [
-
],
whoseprodigiousgraphical inventions ledFunkhouser(
)tocall himthePlayfair
of France. To illustrate, we choose (with some di
culty) an
'tableau-graphique'
(Fig.
.
) by Minard, an early progenitor of the modern mosaicplot (Friendly,
).
On the surface, mosaicplots descend from bar charts, but Minard introduced two si-
multaneous innovations: the use of divided and proportional-width bars so that area
hadaconcrete visual interpretation. hegraph showsthe transportation of commer-
cialgoodsalongonecanalrouteinFrancebyvariable-width,dividedbars(Minard,
). In this display the width of each vertical bar shows distance along this route;
the divided-bar segments have height proportional to amount of goods of various
types (shown by shading), so the area of each rectangular segment is proportional to
thecostoftransport.Minard,atruevisualengineer (Friendly,
),developedsuch
diagrams to argue visually for setting differential price rates for partial vs. complete
runs. Playfair had tried to make data 'speak to the eyes,' but Minard wished to make
them 'calculer par l'œil' as well.
It is no accident that, in England, outside the numerous applications of graphical
methods in the sciences, there was little interest in or use of graphs amongst statis-
ticians (or 'statists' as they called themselves). If there is a continuum ranging from
'graph people' to 'table people,' British statisticians and economists were philosoph-
ically more table-inclined and looked upon graphs with suspicion up to the time of
William Stanley Jevons around
(Maas and Morgan,
). Statistics should be
concerned with the recording of 'facts relating to communities of men which are ca-
pable of being expressed by numbers' (Mouat,
, p.
), leaving the generalization
to laws and theories to others. Indeed, this view was made abundantly clear in the
logo of the Statistical Society of London(nowthe Royal Statistical Society): a banded
he German geographer Augustus Petermann produced a 'Cholera map of the
British Isles' in
using national data from the
-
epidemic (image:
http://images.rgs.org/webimages/
/
/
/
/
/S
.jpg) shaded in proportion
to the relative rate of mortality using class intervals(
<
,
,
,...).
No previous disease map had allowed determination of the range of mortality in any given
area.
