• Two Items due on Stellar today:
• Lab #8
• Project Mini-Proposal
• No new lab exercises or homework
  • focus on individual project work
  • especially, do you have appropriate data for useful spatial analysis

Today

• Initial feedback & discussion of test
• Project presentation tips (using Cherrie Abbanat's slides)

Test Feedback

• Test could be an (abbreviated) example of a possible project
  • Test focus: examining bike routes and bike rack patterns in Chicago
  • Project focus: who benefits from bike infrastructure; why are they done in a particular way; what obstacles limit bike usage in American cities
  • Project would require a little more digging and spatial analysis
  • Project could provide context and first step in a longer study
• Answers will be online by Monday's lab
  • Hopefully, grading will be done by then as well
• Comments on common issues and difficulties
  • Test data source
    • I forgot to add it to the test! (Shan found the data and provided these URLs)
    • Chicago GIS data: http://www.cityofchicago.org/city/en/depts/doit/supp_info/gis_data.html
    • Census 2000 data: http://www2.census.gov/census_2000/datasets/Summary_File_3/Illinois/
    • Another useful link: http://www.cityofchicago.org/city/en/depts/doit/provdrs/gis.html
  • Data Queries
    • Queries could be done in Access or ArcMap
      • But, Access table had all of Illinois - need to join with Chicago-area table
    • When dividing to get percentages, zero-demominator can cause problems
      • First select tracts with non-zero entries
      • Or be sure the calculation worked for all but the non-zero entries and put NULL in the rest
    • Join-by-location is easiest way to move census tract ID to the bike rack attribute table
  • Test ambiguities
    • Bike rack 'location' - we intended that you consider each attribute record to be a separate location
      • Even with TotInstall>2 restriction, some records have the same lat/lon locations
      • We accept counts that are either number of rows or (if you tell us what you did) unique lat/lon
    • Bike route count - we intended that you consider each attribute record to be a separate route
      • Records are polylines not individual line segments
      • But, in some cases, multiple records show the same address so distinguishing 'routes' could be tricky
      • We accept counts that are either number of rows or (if you tell us what you did) unique addresses
  • Mapping
    • Hard to get all of Cook County on page while still seeing useful detail
      • Turning off track outline can help
      • Adjusting symbology high/low range can limit size of bike rack symbols
    • More than one classification choice is acceptable
      • Consider 'standard deviation' to emphasize outliers for skewed distributions
      • We recognize that lab machines have trouble with 'histogram' generation in the classification window
      • Histogram always displays in the 'Statistics' window
  • Raster analysis
    • Try using 'zonal statistics' to get census tract average of distance to CBD
      • We held off adding this to the test!
    • The environment settings for ArcToolbox and for 'Spatial Analyst' menu can be different!
    • You could use the 'neighborhood statistics' tool to measure proximity to college students (similar to the senior citizens density in homework #3)
      • This too was beyond the scope of what we wanted on the test

File organization and performance issues for project work

• C:\usertemp (or C:\temp) are local, desktop and I:\ is not
• Set LOCAL locations in the environment for workspace and (especially) scratch space
• Redundancy can be good!
  • Read-only copy of originals (e.g., test10data)
  • Local working copies
    • proj10_working folder that you move from network to C:\usertemp and back
    • Many MXDs: 11.520_proj10_working1.mxd, 2, 3, ...
    • Use Access: 11.520_proj10_working.mdb
  • Multiple windows (especially in 37-312)
  • Use Data Frames with different joins, coordinates, etc.
  • Open multiple ArcMap sessions along with Access and Excel
    • Just keep the file versions straight
    • And you may need to close files if locked for another use
    • Use Data Frames with different joins, coordinates, etc.
• Refresh issues in ArcMap
  • Sometimes, removing a table and adding it again will add the old version
    • Save ArcMap document, exit ArcMap, and restart - then add table
    • This happens if you edit the table outside ArcMap and do not change the name

Project Presentation Tips

• Cherrie Abbanat's powerpoint slides
• Help from the GIS Services group in the MIT Libraries
  • http://libraries.mit.edu/gis/index.html
  • send email to gishelp@mit.edu
• Poster session at Spring APA meeting (in Boston)
  • Plan to submit an E-sized poster from your project
  • We will accept the poster in lieu of a writeup (but you still must do the oral presentation)
• Monday's Lab (Nov. 22)
  • Work individually on project
  • Discuss project focus and data issues with us
  • Separate 20 minute meeting with undergrads
    • Group discussion about project and CI requirement
    • Meet in 37-312 lab at 2:15 on Monday, Nov. 22