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Assignment 5 - Basic Queries

Format: Text or PDF document. Place on Student Work Zone section of the wiki.

The purpose of this assignment is for you to learn and practice some of the basic queries you can perform with GIS.

In this assignment, you need to perform an analysis in which you use all of the following, in any order or in combination - there are tip sheets for each of these functions on our Tufts GIS Tips and Tutorials site

  • Select by attribute 
  • Select by location
  • Statistics for selected features 
  • Summarize by an attribute field value 
  • Field Calculator or Geometry Calculator 

For example, you could use these tools to analyze parcels in Boston which meet certain conditions for redevelopment based on their attributes and their location relative to other features or demographics, and to prioritize these according to some criteria. Or using MassGIS data you might look for potential land acquisition areas that would serve both environmental ends and provide open space for currently underserved communities. Or you may want to look at what sections of a community may be most vulnerable to a natural or man-made disaster based on census demographics, living/working in hazardous areas, and distance from emergency response facilities and evacuation routes.

It would be ideal to do this assignment as a mini-test of a project idea or at least using data you are likely to use in your project.  If more applicable, use data we have in-house or that you can download online.  But keep it VERY SIMPLE for this assignment! If you have trouble thinking of something, talk to the instructor or TA - we are brimming with ideas.

What to turn in:

Turn in a brief report that includes the following:

  • The goal of your analysis
  • The steps you went through (i.e., the queries you performed, in order) - you may use graphics to show your steps if you like
  • A map or maps that show the results along with summary table(s) you create. The maps do not have to be formal finished maps as in earlier assignments. You can use Snag-it for both the maps and the summary table if you like and simply paste them into your document.
  • A note on why the results of your analysis are or might be incorrect (e.g., a caveat to someone reading or wanting to use these results)

Tips for the assignment

You can use Snag-It to  "snag" graphics of your map or maps and put them in your write up with an explanation of what they are showing - you don't necessarily need to do a full-blown stand-alone map of the same quality as earlier assignments.  Same with tables showing the results of summarizing, or showing statistics - just use Snag-It or the Print Screen function on your computer (press CTRL and PRNT SCRN at the same time, then paste into a Word document).

If the selection tools aren't working as they should

  1. make sure you are using the correct method - e.g., select new set, or select from currently selected set
  2. Click on the redraw icon at the bottom of the screen - we are seeing that sometimes the new selection set doesn't appear until you redraw
  3. Try shutting down ArcMap and restarting with a new map file and only loading the layers from which you are selecting. ArcGIS seems to sometimes just get tired or to run out of memory or something, especially if you have a lot of layers up. Start fresh with just the layers you need for the assignment and it should work.

The biggest problem students have with this assignment is using the Summarize function. You can only use the Summarize function on a category value, e.g., type of land use, openspace owner type, openspace public access (yes, no, etc.).  You will then summarize numeric information by this type (e.g., acres of open space that are publicly accessible, or acres of open space by owner type). Do NOT summarize on a numeric field!

In addition to the tip sheets on the required functions, there are some trouble-shooting tip sheets on our Tip Sheets section that you will find helpful:

  • Creating a smaller data set from a larger one (under Managing GIS Data section of the Tufts GIS Tip Sheets) - this explains how to copy a portion of a GIS data set to your own space (e.g., selecting out parcels from a neighborhood in Boston)
  • Defining a Map Projection - (under Map Projections and Coordinate Systems section of the Tufts GIS Tip Sheets) - if you get a warning that a data layer's spatial reference is not defined, use this tip sheet to help solve that problem.
  • Setting up for Spatial Analysis under Spatial Analsyis Tips section of the Tufts GIS Tip Sheets - this tip sheet tells you how to work with data in different coordinate systems and to get your layers all into one coordinate system
  • Fixing Problems with Numeric and Text Fields using Field Calculator - under Working with Tables section of the Tufts GIS Tip Sheets - this tip sheet explains how to change a text field to numeric and vice versa (e.g., in the Boston parcel assessor data, some of the attributes that should be numeric are instead text, and you need to change them to numeric before querying them (e.g., select all lots larger than 10,000 square feet)

 E-mail the instructor and TA if you have problems!

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