st: Inexplicably missing values for lagged variables

[Clive Gilbert <clivegilbert@gmail.com>]

Dear all,

I am working with panel data and have a number of lagged variables. I
have noticed that some individuals have missing values for certain
years whereas others do not . This is causing problems because I'm
trying to create a scatterplot for a single year so as to provide a
visual summary of my results. However,  the graphs are not very
illustrative of course with some of the individuals missing. My data
set is mostly balanced and the shorter panels I do have don't appear
to account for the irregularities. I'm puzzled.

I think I might be able to get around the problem by select
alternative years for the individuals whose values are missing. But I
have not quite mastered the use of logical operators sufficiently to
be able to do this.

Any advice would be greatly appreciated.

Many thanks,

Clive
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