Part 3 of 3: List 3-5 reasons that immigrant and migrant communities would have statistically lower crime rates than citizens

Part 1 of 3: Does the evidence support the conclusion?
Evidence: Using data on (federal or non-federal) arrests, non-citizens accounted for greater shares of arrests than citizens, proportional to population sizes
Conclusion: non-citizens commit more crimes than citizens

Part 2 of 3: critically analyze the study below
What is the evidence in the study?
What is the conclusion in the study?
Does the study have sufficient evidence to support its conclusions?

Do Illegal Aliens Have High Crime Rates?: High enough, from what we know, to take measures to secure our borders.
Barry Latzer
January 24, 2019
https://www.city-journal.org/illegal-alien-crime-rate-data

Part 3 of 3: List 3-5 reasons that immigrant and migrant communities would have statistically lower crime rates than citizens