GIS Class Session Guide: 21 FEB 2017
- Embrace the conceptual framework associated with database tables as they relate to spatial data! Unlock the magic of joins.
- Acquire US Census / American Community Survey data and manipulate that data using geoprocessing tools into a mappable format.
- Visulize US Census/ ACS data using sound principles of map design
- Kurland and Gorr, Chapter 4: File Geodatabases
- Kurland and Gorr, Chapter 5-6 (Downloading US Census Bureau Boundary Maps), 5-7 (Processing US Census Data), and 5-8 (Downloading ACS data)
Warm-up: Finish creating your layouts of downtown Pittsburgh historical sites, please.
We ended last class with a mini-project of creating an appealing map of historical sites in downtown PGH. The audience for the map was a friend coming to town who wants to spend a day learning about the history of the city and needs a visual guide for doing so.
When you're done, please export the map as a JPEG image file and email it to Eric at firstname.lastname@example.org
Exercise 1: Getting into the guts of database tables
Map data (or more technically, geospatial data) is not organized in a mysterious way. Since computers store information--regardless of type--in essentially the same format, once we grasp the basics of the concept of a database table we can apply that understanding to data that is both spatial and "flat". Our opening exercise will be to actually physically practice joining tables and features so that we can have a tactile understanding of what ESRI ArcMap Desktop is doing in the background when we ask it to join tables. More importantly, we'll be better debuggers of issues that may arise in this process.
- Using the paper data tables from the American Community Survey and the paper output of the TIGER Shapefiles from the US census, practice conducting a table join (an equi join) to create a table of US states and their employment rates.
- Use the GEO.id field in the ACS data to join with the GEO.id field in the state shapefile to conduct the join
- Reflect: What is the value of the Geo ID field? Why not use the state name to do the joining?
Exercise 2: Back to computers - downloading the TIGER files and ACS data
The US Government maintains the most current and accurate database of spatial boundaries in the USA. The Census Bureau also conducts regular surveys of the American population to monitor important social indicators, such as insurance coverage, income status, education attainment, and many, many more. Many projects that have a research or data component to them can benefit from insights that we can gain from the US Census data, so learning how to navigate the tools for accessing the data is a gateway skill for conducting the research.
In class, we'll follow the steps of Tutorial 5-6 in the Gorr and Kurland book to access the census bureau data. We'll then follow the steps in tutorial 5-8 to practice gathering American Community Survey data which, together with the spatial features, allows us to make maps of important household information.
Finally, we'll practice processing that data using spreadsheets and geodatabases so we can transform the data from its original or raw format into a manageable size and format for our needs. We'll use the tutorial steps and tool references from Gorr and Kurland chapter 4 to do this. The important skills from this chapter are:
- Creating a new file geodatabase
- Importing shapefiles into that geodatabase
- Preview, rename, and copy features inside the database
- Compressing and uncompressing geodatabases
- Reading a spreadsheet or comma-separated-value file into a geodatabase table
- Modifying data tables
- Joining data tables to create usable final tables
Exercise 3: Mini Project
This class session involved lots of little steps and picky computer functions. For this mini project, you will practice this set of steps to ingrain them in your brain. Please complete the following:
- Choose a US City or urban area that is of importance or interest to you. Download the TIGER shapefile for that area. Include the US Census tracts for this area and create a layer of just the outline of your target area.
- Review the topics available from the American Community Survey, 5-year estimates. Choose a topic that is relevant to current discussions in the US and choose 2--just TWO--fields to visualize. Download this data table, clean that data in a spreadsheet, leaving only the estimated value and the margin of error columns.
- Pause for a moment and brainstorm 1 or 2 inquiry questions relating to your data. Write it down in a word processor. Example inquiries: "What areas of my hometown are in the greatest need for insurance coverage?" or "How does proximity to a major river correlate with household income?"
- Create a new file geodatabase with an appropriate name for this mini-project.
- Import that table into the file geodatabase you just created.
- Join the feature data with the flat ACS data table.
- Create a compelling map with appropriate symbology to shed light on your question of interest.
- Write a 3-4 sentence (or more) summary of what the map can tell us and how it relates to your core inquiry question.
- Export your map as a JPEG. Email it to Eric and include your inquiry question and findings in the body of the email.