craftgrrl | "Thirding" crochet/knitting patterns?

Can I cut a crochet pattern down to 2/3 of the size simply by multiplying the number of stitches it says to make by 66%? It's a pattern for a stuffed crocheted duck that I bought today and I don't want to make it 7.5" tall. So am I allowed to do that to a pattern (I'm assuming it's OK) or will the proportions be all weird (I'm guessing not, but just wanted to check)?

Thanks girls (and guys), you're the best.

Edit: While looking through the crochet memories of this community to see if the question had already been answered, I found this. These gauntlets are UBER hawt and I totally want to make some--but what the heck is a chain stitch arch? My trusty stitchguide.com doesn't have info on it and I don't know where else to turn.