I did a more thorough analysis of the assault and freedom data and confirmed that violence does increase with freedom, though the data is very highly scattered. “Happiness,” a measure of quality of life, also increases with freedom, and is more reliably correlated with it. It should be noted that what I have been calling “stress” is the difference between 100 percent happiness and actual happiness; so as happiness increases (along with violence and freedom), stress decreases. (See my detailed analysis.)
If your goal is to decrease violence and increase happiness, then you should look for other variables to manipulate. The countries with the best scores in my sample of 44 countries are Colombia and Denmark, which would be good subjects for case studies.