There is a fine distinction between being the source of something and being the cause of something.
The noun “source” means a point of origin or beginning, or one who initiates, generates or supplies something.
The noun “cause” means a reason or motive for an action or condition, or something that brings about a result or effect.
Here’s an example I ran across today while editing:
Lost circulation is the major [cause or source] of non-productive time (NPT) while drilling. Which one works best in this sentence?
Here I would choose “cause,” because NPT is the effect or result. NPT doesn’t initiate with or begin with or originate from lost circulation.
The difference is subtle, but if you think Cause / Effect, Source / Origin, you will be able to make the distinction.
Saw a typo today that cracked me up:
…throughout the project life spam