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Key Ideas in Lab #4:  (Mapping and charting population density in Mass)

1. Review of assignment due dates:
• Lab #3 due today and Homework #2 is now online
• Hwk #1 due this Wed. March 7
• Lab #4 (today) is due next Monday (March 12)
• Hwk #2 part 1 due Wed. March 14
• Lab #5 (vector analysis) next Monday is due Wed. March 21
• In-class (open book) test on Monday March 19
• Hwk #2 part 2 due Friday. March 23
• END OF 11.205 (Friday, March 23) 
• <--- Spring Break --->
• Very preliminary project topic idea due Monday, April 2
• Lab #6 (raster analysis) on Mon. April 2  and due April 9
• This and the rest are required ONLY for 11.188 and 11.520
• Lab #7 (GIS data gathering) on Mon. April 9 and due Mon. April 23
• Hwk #3 part 1 due Wed. April 18
• Hwk #3 part 2 due Wed. April 25 (last homework)
2. Mapping population density with too-detailed a map -- handling one-to-many relationships in ArcMap
   • Tricky to map population density when towns may have more than one part (polygon).
   • Common complication since geometry and data tables come from different sources
   • More common with detailed (large scale & small area) maps - Boston has more than one 'part'
3. Constructing meaningful indices (such as population density)
   • Requires excluding cases and normalizing data
   • May require creation of new features and attributes in writeable directories.
4. Charts and business graphics in ArcMap
   • Another useful dimension: business graphics
   • Careful about which data gets mapped
     • Understand the one-to-many linkages among tables
     • Be aware of selected sets in maps and tables - most operations act on selected sets and you may forget about the selections
5. Handling one-to-many relationships in MS-Access
   • Equivalent to 'summarize' command for ArcMap attribute tables (but more powerful)
   • Need to turn on 'totals' row in the query builder GUI
   • 'Group by' the column(s) you want to collapse into one unique value per row
   • Specify an aggregation function for the other columns (count, sum, average, minimum, ...)

Key Techniques in Lab #4: (Data manipulation in ArcGIS)

1. Joining attribute tables in ArcMap
• Identify matching columns for each table
• Direction matters! start with geographic table
• Join operation will ignore >1 match to any mapable row!
2. Summarizing ArcMap attribute tables:
• Aggregate/summarize all the other attributes for the rows that have the same value in the 'summarize' column
• Highlight the 'group by' column (where each unique value results in one output row)
• Select other columns that you wish to aggregate (via 'count,' 'sum,' 'max,' etc.)
3. Charting the correct table
   • May need to 'summarize' a table before charting
   • Be careful about which table to join to maps (i.e., the one-to-one table after summarization)
   • Selecting on map can impact chart as well as highlighting attribute table rows (if correct tab is checked)
4. Copying web services into ArcMap from earlier ArcMap documents
• Open 11.188_lab2_web.mxd and copy web services into your Lab #5 document
5. Moving tables from ArcGIS into MS-Access

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