I have seen that the ACS USA survey sample increases year by year, and I would like to know if when you make ACS survey, do you follow the individuals along the years and add more, or you change them for each year ACS survey? I mean for example: a person who did the survey in 2002, do it in 2014 as well?
The IPUMS USA samples are all either US Census samples or American Community Survey samples. Both of these surveys do not follow individuals from year to year. Rather they take a random sampling of the US population independently each year. For more details on the sample designs of the samples included in IPUMS USA, see this link. If you are interested in using data that follows households for several samples, I’d encourage you to look into IPUMS CPS. The Current Population Survey follows households for four months, then excludes them for eight months, and then includes them for four additional months. For more details on the sample designes of the samples included in IPUMS CPS, see this link.
I hope this helps. Let me know if you have any additional questions.