It is 1/5, and they follow it quite accurately: Jango is without his base about 37/38 cm, which then means he is 1,85 m. Padme is without her base about 35 cm, which means she is 1,75. Seems accurate to me.
Even the Jabba statue is right: he is about 68 cm tall, which means he is about 3,40 m. In the movie he is 3,90 m, but the tail of the Jabba statue isn't straight, which causes the difference of 50 cm.