No, the second return of GetGuildRosterInfo() is a string - the actual name of the rank.
http://wowprogramming.com/docs/api/GetGuildRosterInfo
Is Newbie the actual name of the rank you want to check for? I noted that you need to replace that with whatever you're looking for.
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"You'd be surprised how many people violate this simple principle every day of their lives and try to fit square pegs into round holes, ignoring the clear reality that Things Are As They Are." -Benjamin Hoff,
The Tao of Pooh