Why is the number of observations for employed (empstat=01,10 or 12) smaller than the sum of fulltime and parttime

According to my tabulation, the number of observations employed (empstat=01,10 or 12) is smaller than the sum of observations working fulltime or parttime (fullpart=1 or 2). This is so weird because the number of individuals working fulltime and parttime should add up to the number of working people.

The discrepancy here is due to a difference in the reference period of each variable. FULLPART records the full-time/part-time status of respondents who were employed during the previous calendar year. In contrast, EMPSTAT refers to respondents’ employment status over the past week. As a result, FULLPART will capture a larger number of employed persons.

Hope this helps.