How to calculate the difference between two observation on different rows

[Trus]

 Hi,

I have a table that shows an ID and two numeric variables, as in the example below:

ID	VAR1	VAR2
ID1	20	10
ID2	21	11
ID3	22	12

I have to add in this table an other column (e.g. TOT) that calculate the difference between var1 to the first row and var2 to the second and so on, as in the example below:

ID	VAR1	VAR2	TOT
ID1	20	10	9
ID2	21	11	9
ID3	22	12	22

Could anyone help me?

Thanks for your assistance.

[Trus]

I have a table that shows an ID and two numeric variables, as in the example below:

ID	VAR1	VAR2
ID1	20	10
ID2	21	11
ID3	22	12

I have to add in this table an other column (e.g. TOT) that calculate the difference between var1 to the first row and var2 to the second and so on, as in the example below:

ID	VAR1	VAR2	TOT
ID1	20	10	9
ID2	21	11	9
ID3	22	12	22

Could anyone help me?

Thanks for your assistance.

[s_lassen · Accepted solution]

data want;
  merge 
    have 
    have(keep=var2 rename=(var2=next_var2) firstobs=2) 
      end=done;
  if not done then
    tot=var1-next_var2;
  drop next_var2;
run;
  

[Trus]

Thank you so much!