Linked Questions

0 votes
1 answer
239 views

what exactly does correlation mean [duplicate]

what exactly is a correlation of zero meant to be, does that mean that changes in x does not affect y, if that is the case, from the scatter plot That is completely false, as sometimes as x increases,...
Chukwudi Ogbonna's user avatar
0 votes
0 answers
40 views

Pearson Correlation Question [duplicate]

I am a beginner on calculating correlations and I would like to ask possibly a very simple question. If I have two variables that I want to perform correlation on, and those variable are of unequal ...
and_apo's user avatar
  • 113
286 votes
11 answers
168k views

How would you explain covariance to someone who understands only the mean?

...assuming that I'm able to augment their knowledge about variance in an intuitive fashion ( Understanding "variance" intuitively ) or by saying: It's the average distance of the data ...
PhD's user avatar
  • 14.8k
132 votes
6 answers
226k views

How would you explain the difference between correlation and covariance?

Following up on this question, How would you explain covariance to someone who understands only the mean?, which addresses the issue of explaining covariance to a lay person, brought up a similar ...
pmgjones's user avatar
  • 5,831
43 votes
3 answers
38k views

What is compound symmetry in plain english?

I recently realized that a mixed-model with only subject as a random factor and the other factors as fixed factors is equivalent to an ANOVA when setting the correlational structure of the mixed model ...
Henrik's user avatar
  • 14.3k
18 votes
4 answers
18k views

Can somebody illustrate how there can be dependence and zero covariance?

Can somebody illustrate, as Greg does, but in more detail, how random variables can be dependent, but have zero covariance? Greg, a poster here, gives an example using a circle here. Can somebody ...
user11883's user avatar
  • 181
16 votes
2 answers
21k views

Does covariance equal to zero implies independence for binary random variables?

If $X$ and $Y$ are two random variables that can only take two possible states, how can I show that $Cov(X,Y) = 0$ implies independence? This kind of goes against what I learned back in the day that $...
steven hurwitt's user avatar
22 votes
1 answer
4k views

How to understand the correlation coefficient formula?

Can anyone help me understand the Pearson correlation formula? the sample $r$ = the mean of the products of the standard scores of variables $X$ and $Y$. I kind of understand why they need to ...
Aaron Lu's user avatar
  • 321
9 votes
3 answers
4k views

Basis of Pearson correlation coefficient

Pearson correlation coefficient is calculated using the formula $r = \frac{cov(X,Y)}{\sqrt{var(X)} \sqrt{var(Y)}}$. How does this formula contain the information that the two variates $X$ and $Y$ are ...
pranphy's user avatar
  • 971
8 votes
2 answers
4k views

Physical meaning of correlation?

Assume that X depicts a random variable denoting the time it takes someone to sweep the floor today and Y be the time it takes him tomorrow and Z be the time it takes him on the last day of October. ...
user avatar
2 votes
1 answer
44k views

Correlation between numerical and categorical data in R [duplicate]

I have a dataset with over 20 variables. Some of them are numerical and some of them are categorical: ...
mace's user avatar
  • 133
4 votes
2 answers
18k views

How to calculate error of percentage ratio?

I have the following problem: I am counting a subset of cells from a tissue in Drosophila (fruit fly) at different days after "birth". At Day0 I obtain a population of flies, and dissect some of these ...
Fomb's user avatar
  • 61
6 votes
1 answer
3k views

Why would we ever use Covariance over Correlation and Variance over Standard Deviation?

I am unable to understand the practical use of Covariance and Variance. In my understanding, Covariance and Correlation are both measures of how one variable changes with respect to another. The only ...
dev's user avatar
  • 163
-2 votes
1 answer
4k views

What does this scatterplot mean? Uniform distributions? [closed]

I am very new to statistics and prob theory: I am looking at a scatter plot of two random variables, both uniformly distributed on $(0,1)$. The plot is approximatively a straight line, and the book ...
Polak's user avatar
  • 1
1 vote
1 answer
8k views

What does it mean for two variables to be uncorrelated? How is it possible for two variables to be strongly related but still uncorrelated [duplicate]

What does it mean for two variables to be uncorrelated? How is it possible for two variables to be strongly related but still uncorrelated
marian's user avatar
  • 11

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