I have been using IPUMS USA extract from 1940 to 2013 using default sample on the website.
So I’ve been trying to detect discontinuities in the data for education attainment at or following the year the changes to compulsory schooling laws were effected.
What I think easy to interpret way of looking at the data is plotting or tabulating the share/number of people against the year a certain cohort turned 16 (yearat16) by each category of educd variable for a particular state. The year aged 16 variable is created simlply by adding 16 to the birthyr of oservations. I have also restricted the sample to age in range 18-64, nonmissing education report (educd >= 2 & educd <= 116) and us born citizens.
I do not think that this way of presenting the data is somehow fundamentally wrong or alters the data in weird way. But what I find is very strange to my eyes. I see that number of total observations with nonmissing education report (and by each category of education) falls as yearat16 (or equivalently birth year) rises.
So what I wanted to ask if any of you know a specific reason for that? Or if you spot any fault in my method?
I would appreciate your help very much!