What to do if your research idea has already been published? I am an amateur researcher (no PhD, Masters, etc...) and just want to put something out there so I can put it on my resume to demonstrate I know how to perform research and hopefully get a job.  I did a Google search and found a paper that discusses the same idea I had.  However, the paper approaches the problem differently than I would have done (although the more I read the harder it is for me to separate the two in my head), and does not go as in depth as I plan to.  With that said, the underlying concept/theory are the same.
It seems like what I can add to the field are additional evidence that the technique works and maybe (most likely not) an expansion of the technique/theory to allow for it to be used more broadly.  Realistically, I'll probably only be able to offer additional evidence that his technique works, as I am not educated enough and in the field - but one never knows.  I'd have to dig deeper, and will only know after I run my simulations anyways to see if the concept can be expanded.
Is there a case for me to construct a research paper?  Or should I just do a bunch of simulations, which is what I was planning on doing, to demonstrate that his technique works and show how it could be applied.  In the latter case, if my work is deemed unoriginal, I would just publish the results either via a blog or Twitter and reference the original paper or just keep it for personal use/knowledge.  In the former case, if my work is deemed original, I would actually write up a research paper, but still obviously reference his paper.
Thanks!
It is hard to give advice specific to your case without knowing more, so I'll mostly restrict to general comments here. What you do depends on the field, to some extent, and to the individual paper and kind of research.
But, if you use a known technique to reach a known result, your results are probably not going to be published. It is, at best, a learning experience.
Independent researchers have a number of problems, but they often come down to lack of professional advice in getting started in research. Working with a guide can help you avoid dead ends. The big problem is that there is a lot to know about any given narrow subject and it can take a long time to absorb it. A guide can help you find an appropriate path to learning what is already known and what is still valuable to pursue. Ideally, you'd like to know about the earlier work before you spend time that might not be productive.
You don't suggest that your research is in mathematics, but there, it is possible to publish new proofs of known theorems under certain circumstances. A proof give insight into why something is true as well as the fact that it is. Sometimes those insights can be transferred to other problems yet unsolved. So, a new proof, using a novel technique, can be valuable in itself and might get published.
Another kind of research depends on statistical methods. Social science and some of the &quot;hard&quot; sciences can use such methods. Some of the published results here are worth replicating, since statistics alone only give evidence, not proof, that something might be true. But, again, you need some variation for the new study to be valuable. Sometimes a paper will contain assumptions that may be unwarranted (normal distribution of a variable in a population, say) and a new study making fewer assumptions might be worth doing. Likewise, some medical studies are extremely important and may affect people's health. So, a lot of evidence for what is really going on is needed and replicated studies can be essential. And some studies actually refute the results of others, thus requiring more study. Statistical studies, if done well, have a measurable probability of producing misleading results. Replication reduces the probability of error, provided that things are done properly, and probably with some variation on the original.