# Tag Info

Accepted

### Does no correlation imply no causality?

does an absence of correlation imply absence of causality? No. Any controlled system is a counterexample. Without causal relationships control is clearly impossible, but successful control means - ...
• 21.1k
Accepted

### Does correlation = 0.2 mean that there is an association "in only 1 in 5 people"?

The quoted passage is indeed incorrect. A correlation coefficient quantifies the degree of association throughout an entire population (or sample, in the case of the sample correlation coefficient). ...
• 20.4k

### When to remove insignificant variables?

Let me first ask this: What is the goal of the model? If you are only interested in predicting if a customer will buy, then statistcal hypothesis tests really aren't your main concern. Instead, you ...
Accepted

### Is there any relationship among cosine similarity, pearson correlation, and z-score?

The cosine similarity between two vectors $a$ and $b$ is just the angle between them $$\cos\theta = \frac{a\cdot b}{\lVert{a}\rVert \, \lVert{b}\rVert}$$ In many applications that use cosine ...
• 13k

### Generate a random variable with a defined correlation to an existing variable(s)

I will describe the most general possible solution. Solving the problem in this generality allows us to achieve a remarkably compact software implementation: just two short lines of ...
• 328k
Accepted

### Generating correlated binomial random variables

Binomial variables are usually created by summing independent Bernoulli variables. Let's see whether we can start with a pair of correlated Bernoulli variables $(X,Y)$ and do the same thing. Suppose ...
• 328k

### Example where $X$ and $Z$ are correlated, $Y$ and $Z$ are correlated, but $X$ and $Y$ are independent

Intuitive example: $Z = X + Y$, where $X$ and $Y$ are any two independent random variables with finite nonzero variance.
• 3,989

### When A and B are positively related variables, can they have opposite effect on their outcome variable C?

The other answers are truly marvelous - they give real life examples. I want to explain why this can happen despite our intuition to the contrary. See this geometrically! Correlation is the cosine of ...
• 2,246

### Interview question: If correlation doesn't imply causation, how do you detect causation?

There are a few ways around this. You are right that A/B testing is one of these. The economics Nobel this year was awarded for the pioneering of field experiments in the study of policies against ...
• 938
Accepted

• 4,067