These are the primary ones I see:
- Narrowing the data to "gun-related" homicides instead of overall murder rates. This is the #1 tactic I see that goes unchallenged. It makes no sense, particularly considering how often guns are used to protect lives. This would be like narrowing the question of terrorism to Muslim-related terrorism to justify Muslim bans. Totally dishonest and evil.
- Excluding data from "underdeveloped" (dog whistle for poor and brown) countries and comparing only to mostly European countries that already had much lower murder rates long before they started implementing gun restrictions. The inner cities that are driving America's murder rates in many ways have more in common with Caracas than Copenhagen.
- Getting very loose with categories like "mass shootings" and "school shootings" that aren't consistently defined across countries. This is how they generate some of their most sensationalist statistics and if you look under the hood, they're almost always total garbage (e.g. classifying reported gun shots near the parking lot of a school at 2am on a Saturday as a school shooting).
- Using raw numbers or per capita numbers depending on whether or not it suits them. They love to share the raw number of mass shootings until you break it down by mass shooting death rate per capita. Then there are several countries, including Norway, France, etc., that have higher rates than America.
When I engage these people I'll often see them cycle through all 4 multiple times even after they've been debunked. It's like playing whack-a-mole.