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I want to calculate the percent change for median household income in Los Angeles at the block group level from 2000 to 2010. Someone told me I have to reaggregate 2000 block data to 2010 block group geography, do a spatial join based on centroid, and that I have to download "crosswalk" or relationship data from the U.S. Census comparing 2000 to 2010. I downloaded the relationship .txt file with 2000 California Census tabulation data and the 2010 tabulation data. Right now I have the unjoined data files. I don't know what to do next. What do I join together?

1) Can someone give me step-by-step instructions on how to calculate the percent change at the block group level? :/

2) If calculating it at the block group level is too complicated, I may just change my level of analysis to census tract level. How do I calculate the percent change at the census tract level?

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If you want to use Census tracts the good people at Brown University have already done the hard work for you:

Brown University Longitudinal Tract Database

This resource contains tract-level variables from 1970-2000 interpolated to 2010 boundaries, facilitating longitudinal analysis.

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This is great! How do I use the crosswalk data? – KTA May 15 '12 at 19:32
From what it sounds like you don't even need to use the crosswalk files. The researchers at the US2010 project have tabulated a whole host of variables for you from the various Censuses, including median household income (also stratified by race/ethnicity). Just go in and download the files and everything will be there for you; they can then be easily joined to your 2010 tract feature class ('trtid10' or 'tractid' corresponds to 'GEOID10' in the Census TIGER/Line files). – qgeog May 16 '12 at 13:02
The crosswalk files are intended for users who have other historical tract-level variables, not available in the pre-made Brown files, that need to be interpolated to 2010 boundaries. They provide instructions to do this in either Access or Stata on their site. – qgeog May 16 '12 at 13:05

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