Law /
Weapons laws in Poland. Carrying a concealed handgun? [918]
You are again comparing rich rural areas of the US with entite countries. And in this case you are comparing total murders not gun murders.
The six Sigma refers to numbers of standard deviations from the expected result - so for example if there are 35 OECD countries, industrialised democraces iwith market economies, then the chance that each country has of having the highest rate of gun violence is one in 35.
The chance of one country having the highest gun murder rate 30 years in succession is one in 35 to the 29th power. That is a number that will break your calculator. It is also a number there is many standard deviation is away from the expected result.
Of course you can use linear regression to handle many more than three predictive variables - some companies like facebook use regressions and algorithms with even hundreds of variables, probably the same kind they use to interfere in your elections. The only problem is that you need to have many events to cover many variables - in the case of the US then half million gun murders over the last 20 years should be a significant enough sample size.
Of course once you get to this point in your statistics classes you can always revolutionise the academic thought on this issue by showing clearly that there is no correlation.
Given that there are no hard borders between US states; then the level of gun control at state levels is only a minor deterrent to petty or hardened criminals. Gun laws in Chicago did not matter if you can buy guns and ammo in Gary or Milwaukee and drive them to Chicago in an hour or so. That takes less than a minute of reasoning to work out.
Thank God my kids don't have to worry about school shootings. Not sure why they have never been any in Poland - maybe because we don't allow any Muslim hordes in or maybe because it's impossible to get hold of guns without a psychological test