7. This is the result. We need to convert this data into Database file (DBF), so it Can be joined to census tract boundary file (Middlesex County). To download the file, You click print/download menu, and click “download” menu. Fortunately, US Census provide the Data in the form that we want. Click “Microsoft Excel” from Database compatible format
8. When you download, the website will provide output.zip file. You need to upzip (extract) the file, and put those files into your working directory (in our case, c:IS directory) There are several different files. You need open the following file and convert it into database format which can be joined to Census tract boundary file. Dt_dec_2000_sf3_u_data1.xls
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10. This is the sample excel file. For mapping purpose, we only need a key column (a unique identifier for census tract), and variables (the ones which we are interested in mapping). Save the file as “MHINC.dbf”.
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14. To be able to join the data from another table, we need to identify which variable can be used as a key variable. In this case, we can use: “ STFID” from tgr34023trt00 file and “CTRACTID” from MHINC.dbf file.
15. In this example, we will use STFID and CTRACTID to combine the two databases because they hold the same data and will correspond with one another.
16. To join data file, you right-click on the tgr34023trt00 and get menu, and choose Joins and Relates. Click Join. You need to choose corresponding variables and table. After you click OK, you will have “Create Index” box, click Yes. Once you click OK button, nothing happens on the screen. But the data is already joined. We can view by checking attribute table.
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