I won't guarantee accuracy since I only checked one source for J-3 specifications.
Full size is 35' 3" WS
Goldber Anniversary is 76.5" WS

18.08% of full size which is between 1/6 and 1/5 scale. Sport scale kits are notorious for not being "scale". During the design and manufacturing process, many compromises will be made to obtain the best yield when cutting parts or desired flying characteristics. The emphasis is on profitability, not true scale adherence.

Of course, if an aeronautical engineer with model aircraft design experience jumps in and proves me full of it, then my name is really J Smith and Texas Don hijacked my identity to post this.