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1 vote

Is 'High School', 'Graduate', 'Unknown' ordinal or nominal data?

Education level is ordinal, as you already noticed. However, you cannot consider "Unknown" as one of the ordinal levels, it is missing data, so what you need to do is pick one of many ...
  • 124k
0 votes

Comparing two clustering methods with adjusted Rand index - How to make labels match

I wonder why the OP said the two clustering methods couldn't be compared, if they have different labels for clustered observations. Note that Rand indices can even be used to compare partitions with ...
1 vote
Accepted

Is 'High School', 'Graduate', 'Unknown' ordinal or nominal data?

The variable Eduction with levels 'Uneducated', 'High School', 'College', 'Graduate', 'Post-Graduate' and 'Doctorate' is certainly an ordered categorical variable. Indeed, we all agree that these ...
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2 votes

What is "better-than-random" precision in clustering?

The authors mean to say that the achieved Precision is better than the baseline Precision we would get at random. For example, if we have 1000 examples with 200 being positive and 800 being negative, ...
  • 37.6k
1 vote
Accepted

Probability that x-axis perfectly separates clusters

Yes, you are exactly correct. Here is an illustration, which also shows you can easily simulate questions like this one to sharpen your intuition: R code: ...
1 vote
Accepted

Do you use the PC1, PC2, PC3 or do you use PCA for feature selection in supervised learning?

I will try to outline a high-level answer to your points, even though there seems to be some confusion about what PCA is doing and how you can use it in your ML framework. PCA finds the components of ...
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1 vote

Using correlation as distance metric (for hierarchical clustering)

I'll expand a bit on the accepted answer to show that in case we've standard-scaled the input data (let's assume it's n-dim), then both euclidean and correlation based distance metrics are just scaled ...
0 votes

How to cluster diverse elements while respecting the original sorting sequence?

This task could be solved by a clustering, but it is actually a sorting problem. One of easy ways to solve it would be... Assign each case its sequential id: ...
  • 53.9k
0 votes
Accepted

How to measure the similarity of an object is to its own cluster or to other clusters

@ttnphns could you compute the average distance with example for my code I'll give the general guide for that. Average distance between every point and every group of points Let $\bf D$ be the square ...
  • 53.9k
0 votes

What exactly does PCA show that I can't figure out otherwise?

"If we wanted to retain our original feature set but wanted to reduce it in some way, why not just pull out extraneous variables that are highly correlated?" PCA gives you linear ...
0 votes

Cluster analysis and chi square test

Was the variable "having a smartphone" used in the cluster analysis? If so, that would invalidate the chi-square test. Otherwise, it should be OK ... but as for your conclusion Can I ...

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