MAPPING AN ACBL DATABASE
A MAP CAN BE MORE THAN A PRETTY ILLUSTRATION: IT IS A POWERFUL
RESEARCH TOOL THAT CAN DIRECT QUESTIONS AND ANSWERS
Sandy Arlinghaus, email@example.com
Look over my shoulder as I map the database obtained from the
ACBL. Rick Beye, Carol Robertson, Ed Evers, and Richard Oshlag
have been extremely helpful in specific ways and Jay Baum has been
helpful in general ways.
There might be many reasons to map a database. One reason is that
all databases have errors in them. Looking at them from different
vantage points enables one to catch errors and correct them.
The database I'm working with has information about each ACBL
district. It's separated into subsets, one for each of the 25
districts. Each subset contains zipcodes within each district and
also units within each district. That is the general idea.
Maps are made from zipcode information. When all the zipcodes are
partitioned into the 25 separate districts, the map appears as in the
first image below (Figure 1). The zipcode mapping is for the US
only (what was in the database). I've put other maps for Canada
and Mexico in, as well, to present the full picture. The Yukon
was assigned to District 19 (in pink) and the Northwest Territories
were assigned to District 18, in blue, because a check of the member
database showed that that was where the majority of members in those
regions had been assigned.
Figure 1. ACBL land---notice the gaps (in black) in the
underlying database. The map is a picture of a database.
Figure 1 is quite revealing when considered as a picture of an ACBL
database. Here are a few items to consider, all of which involve
issues of assignmet of zip code polygons to ACBL districts (from the
database I'm using...):
Take a closer look using Figure 2, below.
- the Swiss Cheese effect--notice the black holes inside most
districts, where the black shows through the color in the US
map. These black holes represent zipcode areas inside ACBL
districts that have not been assigned to any district.
- the Edge effects--there are black holes in districts that are at
the edge. These black holes represent zipcode areas at the edges
of districts that have not been assigned to any district. Look at
the Georgia/Alabama border.
- the Crumbs effect--there are zipcode areas assigned to districts
other than the one in which they lie (inside of or at the edge
of). These zipcode areas are therefore not black but have the
color of their "host" district. Look at the yellow district at
the eastern edge
of New York (district 3) and view it as the "host." Look at the
tiny yellow polygon in Kansas
(yellow inside dark green). Yes, that yellow zipcode area in
assigned by the database to district 3 in New York as its host district.
Figure 2. A closer look at Figure 1 to illustrate the effects
noted above: Swiss Cheese, Edge, and Crumbs. Colors are
chosen to enhance these effects; a pretty map can also be made but that
is not the point...the map is being used as a research tool to ask
How might we make the map better, and why should we care about doing so?
- The Swiss Cheese effect may come about by having no members
present at this time in those left-out zipcode areas. However, if
obvious assignments are made in advance, then if the future sees
members brought in, they will belong in the "right" spot and avoid
further fragmentation of existing districts. For example, it
seems "obvious" to assign the Everglades zipcodes in South Florida to
District 9, Florida. Direction might be given to management to
fill in the obvious gaps of unassigned zipcodes as an investment in
future database management. Individuals coming into those
polygons in the future may benefit by becoming included quickly in ACBL
dissemination of membership benefits.
- The Edge effect is more difficult to resolve than is the Swiss
Cheese effect and no doubt would involve carefult determination, from
talking to management and Directors, about why it is there. The
reasons for resolving it are as above and also so that it is clear to
ACBL members who might already be there where they belong and who is
their local district director.
- The Crumbs effect might well involve both direction from a
committee to management to correct the assignment to the obvious and
conversation with the various Directors involved in the matter.
For example, did the unusual assignment pattern of a district 3 polygon
in Kansas result from a typo during database entry? Or, did it
arise as some unusual cultural connection not yet known to us?
The reasons for considering such an adjustment seem obvious: is
someone in Kansas really likely to consider that his/her district
director lives in the state of New York? There are other crumbs
that are less far-flung from the host and there may be reasons,
established from contacting appropriate parties, for keeping them as
crumbs (see Figure 3). If not, however, then it may be wiser,
from the standpoint of data management to consolidate the districts and
remove crumbs whenever possible.
Figure 3. Notice a variety of Crumb effects (in light purple,
light brown, olive/gold, and dark green)...some farther-flung than
others. There are also Swiss Cheese effects (in black) and one
combined Edge and Crumb effect (in dark green)
It seems likely that in a large database, one would not see these
effects simply by glancing at the database (or would even know to look
for them). The map shows one quickly what to look for in the
database. Further, data consolidation is important because it can
allow management to streamline the handling of information. When
computers are used appropriately to handle information, they enhance
opportunities for humans to do what they do best--computers are a tool,
and a powerful one at that, that serve humans (they do not replace them
or reduce a need for personal interaction...they enhance those
opportunities when used appropriately--a power saw in the hands of an
amateur is a dangerous weapon; in the hands of a master carpenter it
enhances design opportunities).
Greater detail for those interested....
The ACBL database has fields (columns) for ZIPcode and Unit. I've
added an extra one for District, for mapping purposes. Many of
the Unit entries are coded as "0" and for these entries I have assigned
the zipcode areas to a district. Thus, for example, prior to the
assignment of District 12 "0" unit entries, the map of that district
(in green) appears as in Figure 4. The black holes show where
there is no data. Yet, we who live here know that then all of the
Detroit metro area and most of the ACBL members of District 12 are left
out. The reasons for this involve concerns of conflicting
cultural viewpoint that are hopefully now relegated to the past.
However, residents of the two units involved are free to join either
one and are not assigned by ACBL, on the basis of zipcode location to
Figure 4. District 12, in green, without the adjustment of
assigning zipcodes with a "0" code.
When the appropriate assignments are made, the result appears in Figure
5, below. Correction of this particular assignment problem was
easy. There are numerous assignment problems that are not that
easy (at least for me...they may be for locals in the districts
involved) particularly on the west coast. Adjustment of the
database to reassign "0" zipcodes is a substantial task and one that a
committee might ask be done in the interest of accuracy of database
which in turn translates to efficiency of service to affected
units. I've given it my best shot and the results show in Figures
1 and 2 above.
Figure 5. Assignment of "0" polygons presents a consolidated
view, at the district level.
The map in Figure 5 might suggest that the assignment made solved all
problems. It did, but only at the district level. When one
asks the computer to make the map at the Unit level, there is still the
same difficulty as noted above because zipcode polygons are not
assigned to individual units. The map in Figure 6 illustrates
this problem. The darkest brown area is really two units
displayed as one (notice also some Crumb effects).
Figure 6. District 12 by units...but, there are actually five
units in District 12, not the four displayed here! Click here
to go to a Clickable map of the district--once there,
click on zip code polygons to bring up associated database entries.
The solutions are that one must either assign zipcode polygons by unit
or merge the involved units. Those solutions, however, may not be
palatable to locals even if they are to others from a central
management perspective or from an efficiency of information flow
In brief, maps can guide the decisions we make and the decisions we
make can guide the maps we create.
Let me know the decisions you make about mapping, therefore!
I will be updating this page as I produce more maps. In the near
future, I may map some population (various data sets can be linked to
the map to analyze zipcode areas by the variables within the linked
data sets) and I may make a better looking map, assigning black holes
to districts (but leaving the crumbs alone) and adjusting the color
pattern to a less abrupt one (more visually pleasing but less revealing
in terms of errors). I may also put zipcode generated maps of
districts on Bill's website, in addition to the county generated maps
already there, and I may make unit maps for each district (but there
will be many holes coming from the 0 zipcode areas...still, it might be
There are other maps I've made on the following links:
go to the "Atlas" button (has older district boundaries based on
counties rather than newer ones based on zipcodes).
on Bill's Director website--when you look at these, think about charts,
such as the pie charts, you might like on maps or any other analysis
tools you might like...
a link to a clickable map made for Aileen Osofsky, also as a link on
Bill's website above...again using older district boundaries but
showing how a map can interact with a database, online, and with the
user interaction controlling what appears on the screen. When you
look at this one, think about what other clickable maps you might like.