Thank you very much Matthew, I understand now!
I would have another question: I am analysing how (unintervalled) weekly hours worked varies over time, using Census data until 2000 and ACS afterwards. I noticed that in 2001, the year in which I start using ACS, there is an upward blip in the trend. Is this “normal”/is there anything I should do to make the two data sources more comparable?
I can attach a figure if it helps.
Thanks a lot!