93 questions linked to/from Is $R^2$ useful or dangerous?
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### When to not use R squared [duplicate]

I recently graduated graduate school and am looking for a proof on R squared. Specifically when to not use it. I really remember a professor impressing upon me multiple times not to report R squared ...
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### The larger $R^2$ the better? [duplicate]

I want to show that the variable $X$ is significant. In model 1, I use financial statements variables, other macroeconomic variables and $X$. Here, $X$ is siginificant at a 10% level and $R^2$ is 0....
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### What is a good R^2 value? [duplicate]

I understand the answer to this question is that it entirely depends on the data set. However, this does not help people understand if their model is suitable or whether they should explore other ...
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### What do r (Pearson correlation coefficient) and R^2 stand for? [duplicate]

As far as I understood, R squared explains how much the variation in Y is explained by its linear association with X. And it's used as an indicator for goodness of fit of a linear model. Then when ...
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### How to interpret the R2 in univariate regression analysis? [duplicate]

How to interpret the R2 in univariate regression analysis ?
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### Is $R^2$ useless? [duplicate]

I stumbled on a discussion regarding the usefulness of $R^2$ as a metric. Where $R^2$ is defined as: $$\frac{\sum (\hat{y} - \bar{\hat{y}})^2 } {\sum(y - \bar{y})^2 }.$$ The criticism is backed by ...
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### Mathematically, what are the drawbacks of R-squared in evaluation a regression model? [duplicate]

I kept seeing articles about the drawbacks of R-squared (and that's why we need to have adjusted R-squared). One drawback is that: "Every time you add a predictor to a model, the R-squared increases,...
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### Why are the R-squareds of the subsamples much smaller than the R-squared of the full sample? [duplicate]

I'm hoping to get some intuition on what is happening. My R-squared in the full sample is 10%. When I split my sample into two subsets, my R-squared in each subset is about 1%. I thought the R-...
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### What's a real-world example of “overfitting”?

I kind of understand what "overfitting" means, but I need help as to how to come up with a real-world example that applies to overfitting.
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### Simple linear regression output interpretation

I have run a simple linear regression of the natural log of 2 variables to determine if they correlate. My output is this: ...
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### Pseudo R squared formula for GLMs

I found a formula for pseudo $R^2$ in the book Extending the Linear Model with R, Julian J. Faraway (p. 59). $$1-\frac{\text{ResidualDeviance}}{\text{NullDeviance}}$$. Is this a common formula for ...
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### Is a high $R^2$ ever useless?

In stats we're doing linear regressions, the very beginnings of them. In general, we know that the higher the $R^2$ the better, but is there ever a scenario where a high $R^2$ would be a useless model?...
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### What does it mean for a linear regression to be statistically significant but has very low r squared?

I understand it to mean that the model is bad at predicting individual data points but has established a firm trend (e.g. y goes up when x goes up).