Make Spreadsheet to check for missing obs. in panels. Row is id, column is year, element = 1 if present.

make_panel_present.R

# Calling the panel identifiers as id, year

df %>% 
  mutate(present = 1) %>% 
  complete(nesting(id), year) %>% 
  mutate(present = replace_na(present, 0)) %>% 
  select(id, year, present) %>% 
  pivot_wider(names_from = year, values_from = present)

Need to change id and df and this will produce something like this: