Those are great tools!
I find that connecting you're being outside also helps, but also telling the Parrot the you are going out. I use a prep statement: I am going outside and I will be back. As this process sets in with the Parrot, I will add timing to it.
First, like in the article step out of sight to get the in-house, but out of the room part set in place. Next, I will step-out side, but place myself so the Parrot can see me though the window. I will add in and out of the windows view and also time between as a means of building-up a comfort with and a difference between being outside and being in another room.
Communication!!! Let you Parrot know where you are! I'm in the washroom, I'm in the bedroom, etc... This defines a line of communication and that you are around.
Yes, Parrots are a flock bird, but!!! Different Parrot species are very strong Flock Birds example: Cockatoos. Whereas, Amazons are more social groups and to a leaser degree large flock birds.
Parrots that have a family that is communication with them are more comfortable when individuals are not insight and screaming is replaced by quieter communications calls.