What words should we normally use for x-axis in a economic or finance research paper? For example, in this case (I draw the graph from my own reseach)
In my case, I use:
That blue dots mainly lie under the x-axis implies the decrease in y variable after the event date where the parallel trend assumption is satisfied.
I am wondering if there is any word commonly-used in economic or finance research paper standing for "x-axis" or "x-axis" is already okay to be used?
When saying "x-axis", I mean y=0