No issue with your visualization skills. Nicely done. Two important suggestions however.

First, gabapentin would not be considered an insomnia medication. It's more of a seizure medication that's also used for certain types of pain.

Second and more importantly, it's not valid to take side effect data from separate studies performed on different groups of patients and combine them as you're doing here. You can only consider studies where the drugs were studied head to head in randomized, controlled trials.

An example in case this seems confusing. Zolpidem was developed for insomnia, so it's likely that in clinical trials the patients were selected because they suffered from insomnia. Gabapentin was developed to treat seizures and neuropathic pain, so trial patients were selected were selected for having those conditions. These are different types of patients, and headache occurs more commonly among the kinds of patients who got gabapentin. We would expect that in the gabapentin trial, more patients would report headaches compared with patients in the zolpidem trial - NOT because gabapentin necessarily causes more headaches, but just because that population suffers from headaches more commonly.

Hope this helps clarify. I hope you continue to work with healthcare data, because we all need valid analytics to help us make more informed health decisions. Good luck!