i interpret your statement as asking what are the forms of existing data kaya iyon lang din ang magiging sagot ko sa iyo, evidence naman talaga iyan, existing evidences to be specific, they are evidences available and related to your chosen topic and from them you initiate hypothesis which needs another set of evidence to prove, kaya nga sabi ko you are confusing review of existing data with gathering of new data, so yang belief only has existing data reviewed but believers consider the reviewed data as data to prove their claim, they consider reviewed data as data to prove the claim instead of the data to initiate the claim
nah hehe if we only dwell on what is existing then wala tayong makikitang bago diyan, that's why i do not totally rely on what is conventional (sa sarili ko lang naman)
nah i don't have to know more about it since i'm not interested in becoming a scientist, i only decide with as far as i know about it