I just chose to call it a “completed” suicide rather than a “successful” one.
No, you don’t have to separate completed suicides from attempts. That skews the data. The dataset would be all attempts, and then look at the percentage of attempts using a firearm that were completed, and the percentage of those using other means that were completed.
No. Combining the two sets of data skews them both.
Do you even know the meaning of "skew"?
it's when you have data that is incorrect, inaccurate or not part of a dataset which when combines created a bias or distortion of the results.
For example, if I want to look at the data for COVID deaths, and i don't account for age, co-morbidities, and immunity-compromised patients, those data points would likely skew the results in ways that make any conclusions useless.
By not excluding unsuccessful (incomplete?) suicides from the data, you are skewing the numbers toward a bias -- that being the preconception that having access to gun leads to more suicides. While there is a correlation between guns and the effectiveness they offer over SOME alternative means, the correlation does not indicate that reducing gun access will result in fewer suicides.
Again, if 50% of successful suicides do not use guns, why would you believe taking away guns would necessarily stop a suicide from succeeding if they pick one of the other top 2-3 methods -- which we know were just as lethal as guns for about the same percentage of deaths?
"Skew" is a term i'm very familiar with throughout my career. Setting up reports and charts for high level decision makers requires that the input not be skewed for any foreseeable cause -- else the decisions are being made on erroneously aggregated data.
If you look at the current data, it proves that most people do not use firearms to commit suicide -- successful and unsuccessful combined. The only reason the rate of deaths from suicide without firearms isn't much higher than with is because the people who survive are either incompetent or never really wanted to die. That group already proved non-firearm methods are lethal, so why so many failed attempts? Why are we not concerned with stopping the non-firearm attempts, since there are many more of them?