Hi @yongheelee1212    Something I am missing in ....   Course of Treatment is defined if the therapy given is not part of the previous course of treatment and if the drug is given at least twice in 30 days. So for instance, at the beginning, course of treatment is none. so first requirement is already satisfied but the drug has to be given at least twice in 30 days. Drug 1 from first and second observation would not be first course of treatment because it does not meet the second requirement.  So as you can see from the top picture, drug 2(10/30/2012) would be beginning of course of treatment, hence cot1. The drugs observed from 10/30/2012 to 11/30/2012 is drug 2 and drug 3, hence drugs associated with cot1 would be drug2 and drug3).  cot1 continues until new drug is observed consecutively in 30 days, which is drug4 on 3/5/2013. hence, cot2 starts on 3/5/2013.    COT1 starts with drug1 on 10/16/2012 continues with drug2 and drug3 with 30-day gaps through 2/5/2013. On 2/12/2013 drug1 comes back. Drug4 joins with drug1 on 2/19/2013. Questions are: [1] Hence, COT1 joining with drug4 is deemed to be a new sequence. Is this right? [2] why do you say Cot2 starts on 3/5/2013 when Drug4 was started earlier on 2/19/2013?   ... View more

Another way is to have :   length STR $ 32767;   and use  STR = catx(' ,', STR, Var_name) to collect all variables of interest. STR will be holding Var-names separated by comma or any other delimiter you like.   ... View more

There are two types of Arrays in SAS. One is Named Array and the other is Nameless Array. The former deals with SAS variable-names as a shortcut to represent individual variables. The latter is called _Temporary_ Array. The _temporary_ arrays require the dimension (size) of the array at Compilation phase of a data step.   Your example mixed both the usages. For instance,   data test1; set test; array test{c} a-- c; /*Assuming the part where says "the variable whose value is a number*/ run; You are saying that array TEST has the dimension of C where C comes as part of the data set TEST. The value of C (your 3) is not available at the compilation phase of the Data Step (Data Test1). It needs a constant value as 3. See the following:   data test1; set test; array test{3} a-- c; /*Assuming the part where says "the variable whose value is a number*/ run; This works happily - no errors.    In case of Named array, a better way to declare an array is:   data aa; set test; array test[*] a -- c; run; Here the STAR takes care of the size of the array. Even a better way will be:   data aa; set test; array test a -- c; run; The size of the array is implicitly computed at the time of compilation phase. ... View more

Can't a COMPRESS( ) function simplify the solution for dropping a SPACE? data need; set have; value = compress(value); run; ... View more