[Music]
Hi, I am Alexandra Barker. I am your instructor for Part 2 of this course.
In Part 2, you will learn about the resources that you need in order to access the redistricting data files
from the Census Bureau's File Transfer Protocol Site,
or FTP site for short.
These are resources that you need to have handy before you start working with this data.
You will also learn where to locate these files for download and how to import them into Microsoft Access.
Then you'll learn how to extract the data and analyze it.
We will go over examples of how to work with each of the four files that make up the PL 94-171
Redistricting Data Summary File.
In Lesson 4, we will explore the Redistricting Data Program webpage.
This is where you find critical resources for using this data.
Next,
you'll learn how to locate the files for download.
Then,
we will review the technical documentation about this data,
specifically regarding how to identify geography codes in the metadata.
Next,
we will learn more about the prototype data, legacy format summary file
2020 style that we will be using for this tutorial with a Microsoft Access database shell.
To locate the 2020 Census Redistricting Data files for download along with the documentation
that will help you successfully use this data,
you can click on the link available in the description of this video,
or visit census.gov and use the search bar to search for
Redistricting Data PL 94-171 and click search.
Let's use your first search result.
Now you are at the Decennial Census PL 94-171 Redistricting Data page.
On this page is where you find the Redistricting Data files for download for the 2020 Census,
the 2010 Census, and also the 2000 Census.
To locate the files for download, scroll down
and find the Legacy Format Summary Files hyperlink.
Through this link, you will be able to access Redistricting Data Tables for each state, down to the block level.
So, let's click on the Legacy Format Summary files link.
You are now at the Parent Directory.
Under the Parent Directory, you'll find the folder for the Redistricting file PL 94-171.
You just have to open this folder and you'll see all the files for each state.
They are ready for you to click and download.
Next, we provide you with several resources that are critical for your success using this data.
First, let's review the technical documentation.
Click on the 2020 Census State Redistricting PL 94-171 Summary File Technical Documentation link to open the PDF document.
This document includes every information you would need to know in order to successfully use the redistricting files.
I want to highlight two major areas that I use very often.
One is Chapter 4, Summary Level, basically geography.
In Chapter 4, you'll find a complete list of all the geographies that you can use to access redistricting data.
As you can see, every geography or summary level has a code associated with it.
In Lesson 2, Mary went over this subject.
With this resource, when you extract the files, you can use this code to indicate what geography you wanted the data for.
For example, if you are looking to access data for the tract level,
all you have to do here is identify the code for tracts.
In this case, it would be 140,
and the data that you'll be extracting will be for census tract for the state you selected.
Next, let's take a look at Chapter 6, The Data Dictionary.
I will highlight the table matrix section.
This is very important because it gives you the metadata for the data you are about to extract.
Once you extract the data, you notice that every column is labeled with a code.
Here is where you see the metadata for each code,
so when you look at data for column P0010004,
you know it's about Black or African-American alone.
In Lesson 8,
I will show you how you can add the metadata
to the data you just extracted from the redistricting files.
Let's go back to the main page.
Now under Legacy Format Support Materials, you can access the header records.
Let me show you what this is all about.
This document gives you the definitions of all abbreviations and codes that are included in the datafile.
For instance,
in regards to the GEOHEADERS
if you have a column called SUMLEV, you know it means summary level.
Another important part of the metadata is to know what the topics are within each table,
so click on the tab for segment one, which corresponds to file one,
so when you open your data, like I mentioned earlier, looking at the technical documentation,
the label of each column is a code.
On this tab, you'll be able to see
the metadata
for that column,
basically you'll learn the topic on the data provided for that field header.
Next we have the frequently used Geographic Summary Level Codes.
We created this document to make it easier for you to work with census geography.
Here you see the most used summary levels or geographies for accessing redistricting data.
In Lesson 7, we will go over an example of how to use these codes to change the geography for the data you're about to extract.
Next, we have the Microsoft Access database shell that you can download and use to extract
the files. We already set up a few queries for you to facilitate your process in extracting the data.
We're going to review this in the next lessons.
If you're using SAS as your statistical software, you can import the scripts,
and if you're using R, we also have the scripts here for you.
Last, we have a guide on how to use Microsoft Access database shell.
Together, we'll be going step by step through this guide as we learn how to extract the data and use it in Microsoft Access.
Regarding geography products, if you'd like to create maps using this data,
here is where you go to download your Shape Files.
Now let's go back to the Redistricting Data Program page
and visit the redistricting data program management page.
In this page, you'll be able to learn in more detail about the five phases of the Redistricting Program.
Here you also can access the prototype data that we will be using for our tutorial today.
This is a great resource to practice how to download and extract
redistricting data files.
Keep in mind that for the purpose of this tutorial,
we'll be using datafiles from the 2018 Census Test that took place in Rhode Island.
We will also be demonstrating using it with Microsoft Access.
However, like Mary pointed out in Lesson 3,
if you don't have Microsoft Access,
you can extract the data using R, SAS, Python, SQL, SQLite, Oracle or any other statistical software.
Before we learn how to download these files,
let's first learn about the Datafile Structure and Segmentation.
When downloading the Redistricting Data, you'll be downloading four files,
Geographic header file, File01 that will contain tables P1 and P2. These are population tables.
File02 will include tables P3, P4, and H1, so population data as well as housing,
and then File03 which is table P5
for group quarters population.
In Lesson 2, you reviewed what topics are available from each of these tables.
When using these files in Microsoft Access, you notice that the names of these files are now
2020 PL Geoheader, 2020 PL Segment 1 in reference to File01. Segment 2 will be your File02,
and Segment 3 for File03.
Note that each state will have four files containing data from the state to the block level,
so when you downloading these files,
you will be able to select the state you want to download them for,
and automatically, it will download the four files for you.
Once you import the data into a statistical software, you'll be able to use a geographic
code to select which geography or summary level you want to show this data for.
As a recap of Lesson 4, the 2020 redistricting data files
are available in the redistricting data program page
and again, can be accessed under Decennial Census PL Redistricting Data Summary Files,
right where this hyperlink is located,
along with all the supporting materials.