When trying to convey 'apparently', when do you use, だそう, and when do you use そう?

Question

I have seen both だそう and そう written at the end of a sentence to convey "apparently". Do you use だそう when trying to convey "according to" (によると)?

Answer 1

If the sentence ends in a verb or -い adjective, do not use -だそう. Here's an example:

Nagano has delicious soba: 長野はそばがおいしいです。
I hear Nagano has delicious soba: 長野はそばが>おいしいそうです。
According to the travel agency, Nagano has delicious soba：　旅行会社による>と、長野はそばがおいしいそうです。

If the sentence ends in a -な adjective or a noun, use -だそう:

Mount Fuji is beautiful: 富士山はきれいです。
I hear Mount Fuji is beautiful: 富士山はきれいだそうです。
According to my sensei, Mount Fuji is beatiful: 先生によると、富士山はきれいだそうです。

The rule is this: take the plain form of the sentence (as if you're speaking informally), and add そうです.