# If regression is supervised learning is correlation unsupervised learning?

Regression is often given as a simple example for supervised learning because you have a dependent variable and try to build a model with the independent variables.

Could you say that correlation is a simple example of unsupervised learning because you don't differentiate between dependent and independent variables and try to find a pattern in all variables simultaneously (like with clustering which is always given as the example of unsupervised learning)?

• Can correlation be considered a type of learing at all? Correlation is a parameter of a bivariate distribution, just like mean or variance. Is mean a type of learning then, too? I don't know the answer, so this is an honest question. (Not that I would have an easy time with the regression model.) – Richard Hardy May 5 '18 at 9:35
• @RichardHardy: Another observation is that there are many similarities between linear regression and correlation - see also here: stats.stackexchange.com/questions/2125/… and here: stats.stackexchange.com/questions/108640/… – vonjd May 5 '18 at 10:03
• @RichardHardy: See also my answer here: stats.stackexchange.com/a/344619/230 – vonjd May 5 '18 at 11:08
• @RichardHardy: I don't want to get too philosophical but in the end learning in the ML sense is always nothing else but finding some (statistical) parameters of the data. – vonjd May 5 '18 at 11:38
• I don't have one, sorry about that. Perhaps there are some in earlier threads. There must be. Perhaps here. – Richard Hardy May 5 '18 at 20:01

## 1 Answer

Yes. I would say so. Typical other example for unsupervised learning is density estimation and clustering. To me, there is on a meta level no difference between estimating a density, estimating labels to learn clusters and estimating a correlation.

• However, I don't like the term "learning". I agree that these are "unsupervised" as in they are not given an explicit value to predict. But is the use of the tent "learning" really justified? Correlation is just a number. – Has QUIT--Anony-Mousse May 6 '18 at 17:07