I am curious about the usage of word biasedness, I am unable to find it in Oxford's advance learners dictionary but on the internet. When tried to consult some expert, he said that it's a colloquial expression. So my questions is Is there a word biasedness and should we use it?
Based upon my inability to find it in a dictionary, I would say no. Biasedness is not a word.
Rather, you would modify by comparison saying: more biased or less biased.
Or, better yet, just use the word bias.
Bias in this context will carry the same meaning as biasedness is trying to impart.
As there is the noun bias meaning an attitude based on prejudice there is actually no need for a word formation such as biasedness. Obviously the latter is a word some people use in spoken colloquial language that up to now has not obtained official status by dictionary makers.
But it is interesting to think about the logic of this new word formation. Often people have more sense than dictionary makers and what today is seen as incorrect may be common in the next or in two generations.
Well, what may be the cause for the new word? The noun bias is actually a foreign and exotic word and it is a metapher. It is used in the sense of prejudice, but actually means obliqueness. I might guess that people use this noun not so often as the word biased for prejudiced. And it is not so illogical when people form from the more common word biased a new noun "biasedness" that expresses clearly by its suffix the idea of "the state of being biased".