So taken together, there are at least three big problems with describing a set of things.
1) People are more likely to notice and remember the things which match their biases. This will be reflected in their descriptions, even with honest intentions.
2) People are likely to further shift the description for political reasons to make the described thing appear better or worse.
3) The results may significantly differ according to what weight we assign to the individual items of the set. When speaking about books, do we consider all published (or even unpublished? unfinished?) books as equal, or do we weigh them by number of exemplars printed (or sold?) or by how many people read them (and how often?) or liked them? When speaking about a political movement, do we weigh opinions by the number of people who hold them, by the number of articles (or books? or lectures?) expressing them, or by the number of members who read those articles / books / listen to lectures and agree with them?
So taken together, there are at least three big problems with describing a set of things.
1) People are more likely to notice and remember the things which match their biases. This will be reflected in their descriptions, even with honest intentions.
2) People are likely to further shift the description for political reasons to make the described thing appear better or worse.
3) The results may significantly differ according to what weight we assign to the individual items of the set. When speaking about books, do we consider all published (or even unpublished? unfinished?) books as equal, or do we weigh them by number of exemplars printed (or sold?) or by how many people read them (and how often?) or liked them? When speaking about a political movement, do we weigh opinions by the number of people who hold them, by the number of articles (or books? or lectures?) expressing them, or by the number of members who read those articles / books / listen to lectures and agree with them?