Also important to note a few things about this data, the frequency which people carry and the likelihood of the shooting happening in an area where one isn't legally allowed to carry.
Just 6.6% of Americans have a CCW permit. Some do also open carry, but the number can't be that much higher, and not all of those people even carry regularly, some only do sometimes, let's call it a generous 10-12% carry regularly. Even at 10%, that isn't very many, you're more likely to not have anyone armed around you.
Especially considering that most often, the type of mass shootings we're talking about are public mass shootings, not mass shootings at someone's house party that are gang related. Clubs, bars, schools, theaters, concerts, etc, are by and large areas where you're not allowed to carry. Even some stores like walmart prohibit carrying guns inside (and have had shootings before.) This is also going to lessen the likelihood that someone will be armed to respond. Depending on sources the numbers of how many mass shootings take place in said gun free zones varies wildly. If we're cutting out robberies and gang activity, John Lott at the Crime Prevention Research Center puts the number at 98%, if we're including the gangs, drugs, and robberies, Everytown puts the number at 10%.
For an armed civilian to respond, one of those 6.6% of people has to be legally allowed to carry, and have happened to bring their gun today, and even then they still have a gunfight to win they can easily lose. 22/433 is 5.08% of times an armed civilian was the one who stopped the crime, at 6.6% or even 10% of people carrying, I'm gonna say 5.08% is not that bad and the number could go up if more sane people would carry and be ready to save themselves and others should the need arise.
I feel like this is probably what accounts for why it's twice as likely that an unarmed civilian than one with a gun will subdue the attacker, despite the much greater difficulty and danger of doing so
Just 6.6% of Americans have a CCW permit. Some do also open carry, but the number can't be that much higher
One major flaw in this analysis is the assumption that a concealed carry permit is required.
29 states do not require permits for concealed carry. (These are all red states)
Permits are only required in 21 of the 50 states.
8 of those 21 states require permits, but do not actually issue permits upon demand. These are states like California, New York, New Jersey, Hawaii, etc.
These 8 are all blue states. The people of these states are part of the total number of Americans, but are ineligible to acquire permits. They should not be included. The concentration of permit holders outside of states that don't issue permits is much higher than 6.6%.
The overwhelming majority of active permits are from only 13 states where permits are required and are issued on demand. These are all swing states. Just 13 states are home to most of the 6.6% of Americans who have permits. The concentration of permit holders in these 13 states is much, much higher than 6.6%.
The concentration of guns ranges from virtually zero in the 8 most restrictive states, to well over 10% in the remaining 42 states.
True and all that makes a difference, like in the states with restrictive laws on carry you're less likely to have someone armed to defend, etc. Guns can only be a good defense when they're there.
I'd be interested to find the total number who carry regularly though, but I couldn't unfortunately.