I believe I'm underpaid. I've brought this up with my boss and he doesn't disagree, but did ask that I provide some evidence which he can bring to his boss. I realize the easy answer is "find a different job that will pay you more," but this is what I'm working with at the moment.
The problem is that it's really hard to find data that is specific to my location, specific to my area of expertise, and specific to my years of experience. For reference, I am a developer with 6-7 years of experience in Madison, WI. I am the senior developer on my team.
Our primary language is PHP. That can be frustrating because it puts me in the same bucket as a lot of inexperienced and self-taught people who manage WordPress sites or similar (no offense to anyone who is self-taught or works on WordPress, obviously). I have a degree in Computer Science and a background in software engineering. I believe I perform at a different level than those around me—I do much more back-end coding on imports and things which involve a deeper knowledge of data structures, algorithms, and complexity than a typical CRUD app.
How the heck do I get my boss some data which fits my situation? If you asked a random developer what job title someone who codes in PHP has they'd say I'm a Web Developer, which comes with a significantly lower salary than a Software Developer does. I think my background, approach, and typical work fits that of a Software Engineer much more than that of a Web Developer, and there is no small difference in pay. According to the Bureau of Labor Statistics, there is a ~$30k gap between the pay of a Web Developer and Software Developer. That's huge. Either I am a very well-paid Web Developer or a mediocrely-paid Software Developer. I guess I'd prefer to be the latter, as that leaves more room to grow and earn more.
So, how do I find this data? How do I prove that I should be paid significantly more (a 12-15% raise, at least)? I just had a glowing review, so I'm in a good spot. My achievements are well-known. My value to the company is apparent. I essentially just need to prove that the market says I should be making 12-15% more than I do. The data from the Bureau of Labor Statistics just isn't fine-grained enough to say.