What is the mathematical term used for saying if something increases/decreases it has no effect on another thing?
I was thinking along the lines of "X is not linear with Y" however it seems to give the sense that if X increase, Y will increase (though not linearly). This is not the idea I want to convey.
I want the reader to know that an increase/decrease in X does not necessarily mean an increase/decrease in Y.
Well, if you've read the above paragraph you know what I want, but I need the whole idea of that paragraph packed in a single phrase. (I'd have thought a mathematical term would be useful in this sense (since those words are cool), but that's not compulsory of course).
To be sure, I'm not asking for a mathematical term. I'm asking for a catchy term.