Alien Archives; Dragons and Size

[Tukadian]

Okay so I was looking at the Alien Archives monster creation and I'm a little stumped on how to handle dragons, and where the size characteristic is determined.
I know the first step for creating a normal monster is to take an array, so let's say I want a mainly spellcasting red dragon; then I take the spellcaster array and then add on the appropriate, Dragon Type, the Red dragon Graft from the Dragon entry, and any sorcerer class level grafts if needed.
Now, I can't see at any point in there where you determine the dragons size. Or for any other monster. Is it just a "Make it what you feel makes sense" kind of thing?

[the David]

If it's anything like the pathfinder unchained monster building rules, yes.

[Drejk]

Just give it a size that you think will fit the Strength, hit points, and melee damage you gave it.

[Ellias Aubec]

I would imagine it is based on the creatures base size listed in the book (ie making a kaasatha NPC it would be medium sized, not whatever you wanted). SO just look at the dragon size for the base dragon earlier in the book.