Data Collection and Manipulation
Collection
Much of the data gathered for this project was found on
two
main websites. Statistics Canada
and Statistics British Columbia provided tabular data pertaining to the
lower
mainland and GVRD areas for the years 1996 and 2002. I was able to
attain
police force numbers, crime rate numbers, population numbers,
unemployment
numbers, and some economic numbers regarding the districts and
municipalities
in the lower mainland areas. I was able to use some of the
base map shape-files located
on the S-drive on the SIS computers. This allowed for me to join my
tabular
data files onto a spatial representation of my study area.
Once I was able to find all of the data
needed for my
project I had to manipulate it in order to bring it into ArcGIS and
IDRISI. Firstly
I had to manually create my excel spreadsheet files from the data that
was gathered.
Because of the large amount of information that was gathered, much of
it needed
to be discarded. The excel files were then saved as database files so
that I
could manipulate them in ArcToolbox. Once the database files were in
ArcToolbox, they were converted to feature classes which were then
joined to a
base map of the lower mainland. Together the data was then converted to
a
raster format so that it may be imported and opened in IDRISI. This was
carried
out for several sets of data from 1996 and 2002. The final step was to
convert
the imported raster files into vector files within IDRISI using the
RASTER/VECTOR conversion tool in the drop down tool bar menu.
The majority of this project required the collection and use of
census and statistical data for the GVRD and Lower Mainland areas of
British Columbia. Some of this information was located on the
SIS server computer at Simon Fraser University, while the rest was
collected from searching Statistics British Columbia and Census Canada
websites.
- http://www.bcstats.gov.bc.ca/
- http://www.statcan.ca/
- Data warehouse files on the SIS
lab computers
1. Shapefiles - Several maps were directly taken from the SIS drive
that included GVRD area and municipality shapefiles. These were used as
basemaps for synthesizing all the tabular data collected for the
project.
2. Statistical Data- A large portion of this project required
statistical information. This was collected from the websites
previously mentioned and then converted into Microsoft Excel files.
Information from 1996 and 2002 was collected in order to conceptualize
any possible time trends that may influence the final decision on what
areas need a larger police force contingency. Once into Excel, I was
able to join the information to my existing GVRD basemaps based on
individual distrits.
Manipulation
1. The first step that I carried out in this project was to obtain a
basemap of the Lower Mainland, B.C. A shapefile located on the
SIS computers provided a general basemap that was then Dissolved
in ArcToolbox into its unique districts. This allowed me to join my
Excel files directly to the corresponding district identification
names.
2. Once the tabular data was joined to the shapefile I then exported
them together as a single shapefile. From here the data had to be
converted to a feature class, and then to a raster format in order to
import it into the software program Idrisi.
3. In Idrisi the 1996 and 2002 statistical information was analyzed.
Boolean images were created showing positive and negative correlations
between crime rates, populations, and police force numbers.
4. After creating several maps in ArcMap based on general statistical
information, I then converted my data into Idrisi where several
operations were performed. I assigned some AVL (attribute values
files) to my GVRD vector images with crime rates, populations and so
forth. This allowed me to view my attribute information for each of the
district areas.