I’ve downloaded a dataset of 2011 ACS data & started to create new variables, etc. & used the dataset… but I forgot to add a geographical variable the first time I created the data extract… do I have to order the entire new 2011 dataset again but this time add the variable or can I just create an extract of the forgotten variable & attach it to my existing SPSS file?
You should be able to download the forgotten variable in a new extract and merge it with your previous extract using SERIAL and PERNUM to uniquely identify each individual (you can use a few more variables to increase the likelihood of an accurate match), such as AGE, SEX, and RACE). But to be absolutely certain of the accuracy of your data set you should revise your existing extract request, adding the forgotten variable, and download the data as a single file.
I hope this helps.