Hello
I have a longitudinal dataframe organized in the long format and would like to make
comparison between successive rows if certain conditions apply. Specifically, I have
four variables of interest: grade, score, year, and schid, associated with each school
with 3 measurements per school per grade, therefore the rows are temporally ordered
and each school occupies multiple rows. For example, a school may have grades 4,5,6
and three observations per grade at years 2001-2003 and therefore occupies 9 rows.
So, my goal is to make a comparison between score 1 and 2 (same column, next row) if
the score is from the same school, same grade, but one year later and create a new
binary variable if score 1 < score 2.
Something like, ifelse(data[x,4] with data[x,4], if schid=schid and grade = grade, and
year = year + 1, 1, 0)
So, I will end up with a new variable in the data frame where 1 indicates that
subsequent score is larger than the score for the same grade in the same school in
year t-1.
I'm a little confused how conditional selection would work in such a scenario.
Many thanks,
Harold
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