How to attribute a value of a given variable of a case to its matched control

[arzon]

 Hi dear,

I will be grateful if someone can help me with the following query: 

I have cases matched to controls and I need to attribute a value of a case for a given variable to the corresponding matched control. as detailed in the tables below, I need to attribute the value "1" of the "Varx' of the case to the control (case=0) so that the value of the control for varx become 1 instead of missing. 

Input table;

ID   Macth_ID  case   Varx

1     1a              1        1

2     1a              0        .

Output expected: 

ID   Macth_ID  case   Varx

1     1a              1        1

2     1a              0        1

Thanks in advance for your support.

[ballardw]

Are you implying that your are matching on the Match_ID variable? If so, do you ever have more than two records with the same Match_id? Do you only have one non-missing value for Varx per Match_id?

[arzon]

Hi Ballardw

thanks for replying.

The data are already matched using the match_ID variable that identifies matched case and controls. Each case can have more than one control. Varx (that takes value 0 or 1) is missing for all the controls in the dataset but for each matched control the value of Varx is the same as for the case (i.e., if Varx =0 for the case, it should also be 0 for the matched controls). 

Hope this clarify.

thanks again

[Reeza]

This is a lookup or merge. 

You can use a data step merge or SQL, and the COALESCE() function is helpful.

Examples and explanations can be found here:

http://documentation.sas.com/?docsetId=lrcon&docsetTarget=n1tgk0uanvisvon1r26lc036k0w7.htm&docsetVer...

[arzon]

Thank you reeza for your suggestion and the link you shared. It was helpful.

Have a nice weekend!

[AnnaBrown]

Hi arzon,

I'm glad you found some useful info! If one of the replies was the exact solution to your problem, can you "Accept it as a solution"? Or if one was particularly helpful, feel free to "Like" it. This will help other community members who may run into the same issue know what worked.

Thanks!
Anna