What I noticed is that everyone seems to assume that my problem to understand the sentence ”...within-cluster sum of squared differences...” was regarding “sum of squared differences” and not “within-cluster”. I don’t know the definition of the concept of a mathematical cluster. What might add to the confusion is that I’m not even sure about the meaning of the English word “cluster”. After that I decided to postpone reading the post. I could take the effort to look everything up of course but thought it would be more effective to read it in future.
Your post simply served as an example of how difficult it can be to read Less Wrong without a lot of background knowledge.
What I noticed is that everyone seems to assume that my problem to understand the sentence ”...within-cluster sum of squared differences...” was regarding “sum of squared differences” and not “within-cluster”.
Not really. I actually wrote a basic explanation of the whole sentence concept by concept but trimmed it down to the part that best illustrated dependence on mathematical background. Saying “within cluster is basically a phrase in English that refers to the same thing that’s in the title of the post” wouldn’t have helped convey the point. :P
It does, however, illustrate a different point. There is a trait related not just to intelligence but also to openness to information and flexible thinking that makes some people more suited than others to picking up and following new topics and ideas based on what they already know and filling in the blanks with their best inference. Confidence is part of it but part of it is social competition strategy embodied at the cognitive level.
There isn’t an explicit mathematical concept of a cluster.
Here’s what K-means does. Say, K is 3.
You try all the possible ways to partition your data points into three groups. You pick the partition that minimizes the sum of squared differences within each group. Then you iterate the procedure.
What I noticed is that everyone seems to assume that my problem to understand the sentence ”...within-cluster sum of squared differences...” was regarding “sum of squared differences” and not “within-cluster”. I don’t know the definition of the concept of a mathematical cluster. What might add to the confusion is that I’m not even sure about the meaning of the English word “cluster”. After that I decided to postpone reading the post. I could take the effort to look everything up of course but thought it would be more effective to read it in future.
Your post simply served as an example of how difficult it can be to read Less Wrong without a lot of background knowledge.
Not really. I actually wrote a basic explanation of the whole sentence concept by concept but trimmed it down to the part that best illustrated dependence on mathematical background. Saying “within cluster is basically a phrase in English that refers to the same thing that’s in the title of the post” wouldn’t have helped convey the point. :P
It does, however, illustrate a different point. There is a trait related not just to intelligence but also to openness to information and flexible thinking that makes some people more suited than others to picking up and following new topics and ideas based on what they already know and filling in the blanks with their best inference. Confidence is part of it but part of it is social competition strategy embodied at the cognitive level.
There isn’t an explicit mathematical concept of a cluster.
Here’s what K-means does. Say, K is 3.
You try all the possible ways to partition your data points into three groups. You pick the partition that minimizes the sum of squared differences within each group.
Then you iterate the procedure.