Reliability ACS 2000-2004

How reliable is ACS before the actual implementation in 2005. The sample sizes are much smaller for 2000-2004. Especially 2000 stands out - 587,519 addresses were in the final interview but the data in IPUMS has only 371,618 individuals. Usually there are more individuals in a survey than households interviewed. Did anything happened in 2000? For 2001-2004 the pattern is similar to later years - more individuals in the data than interviewed households. I assume the sample sizes are smaller for 2001-2004 because it was a testing period?

Just wanted to reactivate this thread because it was a while I have posted the question and you guys are usually fast in replying!

Apologies for the delayed response on our end!

You are correct that the sample sizes for 2000-2004 are smaller than those for later years because of the testing period. If you take a look at the sample descriptions, you’ll see that those years have between a 1-in-750 and 1-in-232 random sample, while all later years have a 1-in-100 sample. However, I am unsure why the number of addresses in 2000 is so much greater than either the number of individuals or housing units in the IPUMS sample. I have forwarded this question to our USA team and will let you know as soon as I hear back.

No worries at all! Thanks!