Hi all,

I encountered some problems in graphing xtline diagrams. Here is my code:
Code:
preserve
collapse (mean)coverage, by (high planning finance performance year)
xtset year
xtline coverage , t(year) i(finance) overlay
NB: coverage is the y variable. finance is a category variable that includes 4 categories (finance has level 1.2.3.4, which is shown as line finance =1, finance =2...). The diagram will be like:

I am so confused why the diagram is like this, and only the line of finance level 4 looks normal.

Thanks a lot!

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