Observational data and politics
In the age old debate between socialism vs capitalism (the really existing ones, not whatever idealised versions are theoretically possible) empirical studies are sorely lacking. The debate is somewhat poisoned from the outset, as it does not help that people tend to use the word socialism to mean anything from the smallest welfare state to a fully planned economy, but let’s confine ourselves to USSR and friends for the scope of this discussion.
Jason Hickel in this thread points out to this paper: Cereseto, Shirley, and Howard Waitzkin. “Economic development, political-economic system, and the physical quality of life.” American journal of public health 76.6 (1986): 661-666. The paper makes the claim that socialist countries had better outcomes in a number of indicators such as (quoting) “health, health services, and nutrition (infant mortality rate, child death rate, life expectancy, population per physician, population per nursing person, and daily per capita calorie supply); measures of education (adult literacy rate, enrollment in secondary education, and enrollment in higher education);”
If you look at the thread people are attacking the study for all kinds of reasons (e.g. did it control for different GDPs? deaths from forced collectivisation? Why is there no advanced socialist economy?). Some of these can be answered by reading the paper, but the deeper problem lies in doing causal analysis from observational data in multi-dimensional settings. Almost everything correlational can be used to drive some sort of causal hypothesis, which cannot be easily disproved until a another clear causal pattern through a third variable is found. Proponents of opposing views can keep coming up with variables and hypotheses until kingdom come, and ultimately there is no clear way of resolving the debate once and for all.
An experimental study is obviously impossible (i.e. you cannot take a country, freeze 10000 clones of it, try different politics on each clone and compare outcomes), so it mostly becomes a question of belief/faith and lived experience. Are you happy with things as they are? Then any change will look horrible. If not, it’s up to effective propaganda and force to stop you from crossing the threshold and joining the other side (whichever that maybe). Interestingly enough, there is very little “objective logic” that would come into any such decision, rationalisation would probably happen after a choice is made.