How are dependent variables related to one another?
“The dependent variables should be related conceptually, and they should be correlated with one another at a low to moderate level.” (Course notes from Northern Arizona University) “DVs correlated from about .3 to about .7 are eligible” (Maxwell 2001, Journal of Consumer Psychology)
When is there no correlation between two variables?
When there is no relationship between two variables this is known as a zero correlation. For example their is no relationship between the amount of tea drunk and level of intelligence. A correlation can be expressed visually.
Is the correlation between dependent variables too strong?
The dependent variables in a MANOVA should not be “too strongly correlated”. But how strong a correlation is too strong? It would be interesting to get people’s opinions on this issue. For instance, would you proceed with MANOVA in the following situations?
Why is correlation a measure of linear dependence?
Correlation is a measure of linear dependence, so it kind of gives you an indication of how the two variables are related linearly. It doesn’t capture however more complicated behaviour. but the two random variables are clearly dependent.
What is the formula for the correlation coefficient?
The most widely used correlation coefficient is Pearson Coefficient. Here is the mathematical formula to derive Pearson Coefficient. Explanation: It simply is the ratio of co-variance of two variables to a product of variance (of the variables). It takes a value between +1 and -1.
Can you prove that X and Z are positively correlated?
As we shall see by example, the answer is (perhaps surprisingly) “ No .” We may prove that if the correlations are sufficiently close to 1, then X and Z must be positively correlated. Let’s assume C (x,y) is the correlation coefficient between x and y.