Question

what does the math term unbiased mean

Answer 1

to have ideas which are not controlled by human factors.

Answer 2

well, data collected i guess.

Answer 3

You see, in data collection, the researcher might be biased in his data collection.
So to be unbiased, you have to remove anything which might effect the data.
Sometimes, in experiments, you do this by repeating the experiment ot remove the randomness of the factors.

Answer 4

In external data collection, maybe they collect from a certain group which may not be representative of the entire population. Taht would be biased.