workshop

atcoordinates YouTube Channel

Video Tutorials for Finding US Census Data

I have recently created an atcoordinates YouTube channel that features a series of how-to videos on finding and accessing US census data using a variety of websites and tools. I explain basic census concepts while demonstrating how to access data. At this point there are four videos:

  1. Exploring US Census Data: Basic Concepts. This is a narrated slide show where I cover the essential choices you need to make and concepts you need to understand in order to access census data, regardless of the tool or platform: data set, time period, subjects or topics, and geography. I discuss the decennial census, American Community Survey, and population estimates. This video is intended as a prerequisite for viewing the others, so I don’t have to explain the same concepts each time and can focus on demonstrating each particular application.
  2. American Community Survey Census Profiles with MCDC Apps. This screencast illustrates how you can quickly and easily access census profiles for any place in the US using the Missouri Census Data Center’s profile applications. It’s also a good introduction to census data in general, if you’re unfamiliar with the scope of data that’s available.
  3. Search Strategies for data.census.gov. I demonstrate how to use the Census Bureau’s primary application for accessing current census data, using the advanced search tool and filters.
  4. Using TIGERweb to Explore US Census Geography. I show you how to use this web map application for viewing census geography, while explaining what some of the small-area census geographies are.

I plan on adding additional videos every month or so. The pandemic lock down and uncertainty over whether classes will be back in session this fall inspired me to do this. While I prefer written tutorials, I find that I’ve been watching YouTube more often for learning how to do certain tasks with particular software, so I thought this would be useful for others. The videos average about 10 to 15 minutes in length, although the introductory one is a bit longer. The length is intentional; I wanted to explain the concepts and describe why you’re making certain choices, instead of simply pointing and clicking without any explanation.

Feel free to spread the news, share and embed the videos in research guides or web pages, and use them in classes or workshops. Of course, for a more in-depth look at US census data, check out my book: Exploring the US Census: Your Guide to America’s Data published by SAGE.

QGIS 3.10 Screenshot

QGIS 3.10 Tutorial Workbook

I just posted an updated version of my QGIS tutorial / workbook manual, Introduction to GIS Using Open Source Software. This version was written for QGIS 3.10 A Coruña, which recently superseded QGIS 3.4 Madeira as the current Long Term Release (LTR). The LTR is intended to be more stable than the current releases and is supported for at least a year.

The workbook was designed to accompany a day-long introductory workshop that I teach and is divided into five chapters. Chapter 1 is a broad and concise overview of GIS, chapters 2 to 4 are hands-on exercises that cover: the basics of using the interface and the difference between vectors and rasters (chapter 2), a site selection analysis that demonstrates geoprocessing, spatial selection, table joins, coordinate plotting, expressions, and spatial analysis (chapter 3), and a thematic mapping example that illustrates coordinate reference systems (CRS), data classification, and mapping (chapter 4). Chapter 5 summarizes data sources and resources for learning more about GIS. In chapters 2 to 4 the steps for doing the exercises are kept concise with many screenshots, while detailed commentary explaining how everything works follows.

The manual and tutorial data are freely available for personal and classroom use under a Creative Commons license. I’m providing the material for both 3.10 A Coruna and 3.4 Madeira for now, but will take down the latter at the end of the spring semester (late May 2020).

The changes between 3.4 and 3.10 are not dramatic as far as the basic tools and principles that I cover in the book go, but I thought an update was worthwhile as there are just enough changes that could trip up new users (see the 3.10 visual change log for a full list of software updates).  In addition to incorporating changes to the interface, I also took the opportunity to tighten up and condense the material. In particular, I consolidated the coordinate reference system (CRS) exercises in chapter 4 from two sections to one, because in practice I found that it was overkill for a one-day session.

Here are a few noteworthy changes to the tutorial and software that impact novice users:

  1. The default setting for the toolbar buttons is rather small, so during the setup phase in chapter 2 I inserted an optional step to make them bigger. Go to: Settings > Options > General tab, and under the Application section change the icon size from 16 to 24.
  2. In 3.10, when new files are generated from geoprocessing operations and added to your project, the layers appear in the layers panel with the name you give them. In 3.4 they were assigned generic aliases like “Clipped” and “Buffer” based on the process you ran.
  3. In 3.10 the “Quantiles” classification scheme has been replaced with “Equal Counts”. Same scheme, different terminology.
  4. There’s now a dedicated north arrow button in the map layout screen. In 3.4 and earlier versions you added an arrow by selecting the add image button.
  5. In 3.10, every time you add a layer with a CRS that doesn’t match the existing CRS of the window, you’re presented with a datum transformation screen to modify the file you’re adding. This is a helpful warning if you already have existing layers in your project that match the window and your new file doesn’t, but it’s annoying when you’re trying to add files to a blank window in a new project. You can turn this feature off under: Options > Settings > CRS tab, under Default Datum Transformations uncheck the box for Ask for datum transformation.

It’s hard to believe that this is the 10th edition I’ve published in the past ten years. QGIS has certainly come a long way during that time. For a trip down memory lane, look at the 1st edition I wrote for QGIS 1.5 Tethys in 2011! Back then I wrote the whole thing in HTML… thankfully I “discovered” LaTeX a year later, and have used it for writing tutorials ever since.

If you wanted to learn GIS in general and QGIS in particular, spend a day with the manual and work through the exercises and you’ll have a good foundation. All the basics are there, as well as best practices and the “gotchas” that tend to trip people up.

Updated QGIS Tutorial for 3.4

I recently released an updated version of the manual and data I use for my day-long GIS Practicum, Introduction to GIS Using Open Source Software (Using QGIS). The manual has five chapters: a summary overview of GIS, basics of using the QGIS interface, GIS analysis that includes several geoprocessing and analysis functions, thematic mapping and map layout, and a summary of where to find data and resources for learning more. Chapters 2, 3, and 4 are broken down into sections with clear steps, followed by commentary that explains what we did and why. We cover much of the material in a single day, although you can space the lessons out into two days if desired.

I updated this version to move us from QGIS 2.18 Las Palmas to 3.4 Madeira, which are the former and current long term service releases. While the move from 2.x to 3.x involved a major rewrite of the code base (see the change log for details), most of the basics remain the same. While veteran users can easily navigate through the differences, it can be a stumbling block for new users if they are trying to learn a new version using an old tutorial with screens and tools that are slightly different. So it was time for an update!

My goal for this edition was to keep my examples in place but revise the steps based on changes in the interface. Most of the screenshots are new, and the substantive changes include: using the Data Manager for adding layers rather than the toolbar with tons of buttons, better support for xlsx and ods files which allowed me to de-emphasize xls and dbf files for attribute table joins, the addition of geopackages to the vector data mix, the loss of the Open Layers plugin and my revision to the web mapping section using OSM XYZ tiles, the disappearance of the setting that allowed you to disable on the fly projection, and the discontinuation of the stand-alone Data Browser. There were also changes to some tools (fixed distance and variable buffer tools are now united under one tool) and names of menus (Style menu has once again become the Symbology menu).

It’s hard to believe that this is my ninth edition of this tutorial. I try to update it once a year to keep in sync with the latest long term release, but fell a bit behind this year. QGIS 2.18 also survived for a bit longer than other releases, as the earlier 3.x versions went through lots of testing before ending up at 3.4. When it comes time for my tenth edition I may change the thematic mapping example in chapter 4 to something that’s global instead of US national, and in doing streamline the content. We’ll see if I have some time this summer.

Since I’m in update mode, I also fixed several links on the Resources page to cure creeping link rot.

Census Workshop Recap

I’ve been swamped these past few months, revising my census book, teaching a spatial database course, and keeping the GIS Lab running. Thus, this will be a shorter post!

Last week I taught a workshop on understanding, finding, and accessing US Census Data at the Metropolitan Library Council of New York. If you couldn’t make it, here are the presentation slides and the group exercise questions.

Most of the participants were librarians who were interested in learning how to help patrons find and understand census data, but there were also some data analysts in the crowd. We began with an overview of how the census is structured by dataset, geography, and subject categories. I always cover the differences between the decennial census and the ACS, with a focus on how to interpret ACS estimates and gauge their reliability.

For workshops I think it’s best to start with searching for profiles (lots of different data for one place). This gives new users a good overview of the breadth and depth of the types of variables that are available in the census. Since this was a New York City-centric crowd we looked at the City’s excellent NYC Population Factfinder first. The participants formed small groups and searched through the application to answer a series of fact-finding questions that I typically receive. Beyond familiarizing themselves with the applications and data, the exercises also helped to spark additional questions about how the census is structured and organized.

Then we switched over to the Missouri Census Data Center’s profile and trends applications (listed on the right hand side of their homepage) to look up data for other parts of the country, and in doing so we were able to discuss the different census geographies that are available for different places. Everyone appreciated the simple and easy to use interface and the accessible tables and graphics. The MCDC doesn’t have a map-based search, so I did a brief demo of TIGERweb for viewing census geography across the country.

Once everyone had this basic exposure, we hopped into the American Factfinder to search for comparison tables (a few pieces of data for many places). We discussed how census data is structured in tables and what the difference between the profile, summary, and detailed tables are. We used the advanced search and I introduced my tried and true method of filtering by dataset, geography, and topic to find what we need. I mentioned the Census Reporter as good place to go for ACS documentation, and as an alternate source of data. Part of my theme was that there are many tools that are suitable for different needs and skill levels, and you can pick your favorite or determine what’s suitable for a particular purpose.

We took a follow-the-leader approach for the AFF, where I stepped through the website and the process for downloading two tables and importing them into a spreadsheet, high-lighting gotchas along the way. We did some basic formulas for aggregating ACS estimates to create new margins of error, and a VLOOKUP for tying data from two tables together.

We wrapped up the morning with a foreshadowing of what’s to come with the new data.census.gov (which will replace the AFF) and the 2020 census. While there’s still much uncertainty around the citizenship question and fears of an under count, the structure of the dataset won’t be too different from 2010 and the timeline for release should be similar.