Massachusetts Institute of Technology Department of Urban Studies and Planning 11 520 A Workshop on Geographic Information Systems 11 188 Urban Planning and Social Science Laboratory Lab Exercise 5 Working with 2000 Census Data Overview In this exercise you will extract raw data from Census STF3 files to create a thematic map indicating the percentage of workers in block groups in Middlesex County who drive alone to their jobs You may find the notes from the Making Sense of the Census lecture and Accessing Online Census Data in ArcView a useful reference Your goal is to create a table that contains the percentage of workers who drive alone to work by car truck or van for each block group in Middlesex county Note that unlike the simple example shown in class to complete this task you must normalize the data You may want to look at the section consider a different example for information on the appropriate universe variable Necessary Resources View the Making Sense of the Census lecture notes and the Accessing Online Census Data in ArcView lecture notes for background information on this topic Summary File 3 Technical Documentation pdf local version census web page version Chapter 3 Subject Locator This index is designed to quickly identify the STF3 tables you may need Each table variable is listed alphabetically Identification Section Table Matrix Section Use this section to find the data dictionary number for the STF3 table that you are interested in Chapter 2 How to Use This File One of the most important parts of this chapter is the explanation of how to extract the correct geographic summary level Refer back to the Lab section 2000 Census Variable Locator Once you find the census variables you are interested you can use this file to locate the 2000 Census data file that holds your variable Hints The find tool may come in helpful when trying to find a variable in the 2000 Census Technical Documentation Search for keywords like Means of Transportation to Work and Persons 16 years and over Getting Started Create a Shapefile of Block Groups in the Boston Region Launch ArcView and go to File Extensions to add the MIT Geodata Search Tool This tool allows you to search for data in MIT s spatial database This spatial database holds boundary and statistical data from all over the world The MIT Geodata Search Tool allows you to locate data and add it to your active ArcView view Once the file in opened in ArcView you can perform simply analysis or download the data file to your computer After the MIT Geodata Search Tool is added in the ArcView extensions dialog an icon and menu item will appear allowing you to access the tool Use this tool to find Massachusetts Block Groups for 2000 census Hint Search on all the layers in Massachusetts A results dialog will appear Refer back to the Lab section Press the View metadata button to look additional information on the file Once you find the file highlight it and press the Add selected layer to view button to add the layer to your view Exit the MIT Geodata icon to open up the attribute table for this theme What column Search Tool Use Theme Table or are you going to use to link this coverage to external block group census data In order to work with a smaller file create a new Shapefile that represents the 2000 Massachusetts Block Groups that fall within major Boston area counties Essex Middlesex Worcester Suffolk Plymouth Norfolk Bristol Branstable To create a new Shapefile that represents the 2000 Block Groups in our area of interest Boston area counties we need to select the appropriate block groups and convert them to a new Shapefile To select the 2000 Block Groups in your area of interest you will use ArcView s Select By Theme tool This tool will select features in one theme that intersect with selected features in another To use the Select By Theme tool you need to have a layer that represents the 2000 Massachusetts Block Groups and another layer that represents the U S Counties You will select the Massachusetts counties that define your area of interest and than use that selection to find the block groups that fall within those counties To do this follow the steps below STEP 1 Use the MIT Geodata Search Tool to find the U S Counties Generalized layer Hint Try using Title as you search type Add the layer to the same view as the Massachusetts Block Groups 2000 layer STEP 2 Highlight the Select tool and use it to select Essex Middlesex Worcester Suffolk Plymouth Norfolk Bristol and Branstable counties from the U S Counties Generalized layer When selected these counties should appear yellow STEP 3 With the counties selected you are ready to use the Select By Themes tool This tool works on the currently active theme so you will need to make the Massachusetts Block Groups 2000 theme is active Go to the Theme menu and select Select By Theme When the dialog appears Choose to select features from your active theme Massachusetts Block Groups 2000 that Intersect with the selected features of the U S Counties Generalized file sde data us ma e25blkgrp 2000 Press the New Set button and wait while ArcView processes you request STEP 4 All the Block Groups that intersect with Essex Middlesex Worcester Suffolk Plymouth Norfolk Bristol and Branstable should now be highlighted You are ready to create a new file based on these selected features using ArcView s Convert to Shapefile tool Hint Convert to Shapefile can be found in the Theme menu Call this new theme b blkgrp shp and save it to your working directory STEP 5 In your view remove the layers you added through the MIT Geodata Search Tool We no longer need these file and their size could effect processing speed Form this point you will only need to use the b blkgrp shp file Working with Census Data Finding The Variables To complete the lab you must create one or more files with the subset of the data you need Follow these steps to create the files STEP 1 In order to facilitate your use of the 2000 Census STF3 files for Massachusetts they have been loaded into the Athena locker census The census files we ve saved are located in mit uscensus stf3a2000 but you still have to determine which STF files and data fields you will need for Workers who drive alone to work See Means of Transportation to Work in the Chapter 3 Subject Locator of 2000 Census the Technical documentation Ignore tables whose names begin with Imputation of See below for more information on imputation The universe you will need to normalize