Most meta-analyses are done by people in the field, although I'm not sure whether they're typically experts in the specific phenomenon they're meta-analyzing.
My own impression has been this as well: if you already understand your basic null-hypothesis testing, a regular meta-analysis isn't that hard to learn how to do.
But an epidemiologist meta-analyzing observational studies generally can't quantify confounding biases and analogous sources of systematic error.
Do you have any materials on epidemiological meta-analyses? I've been thinking of trying to meta-analyze the correlations of lithium in drinking water, but even after a few days of looking through papers and textbooks I still haven't found any good resources on how to handle the problems in epidemiology or population-level correlations.
Do you have any materials on epidemiological meta-analyses? [...] I still haven't found any good resources on how to handle the problems in epidemiology or population-level correlations.
Not to hand. But (as you've found) I doubt they'd tell you what you want to know, anyway. The problems aren't special epidemiological phenomena but generic problems of causal inference. They just bite harder in epidemiology because (1) background theory isn't as good at pinpointing relevant causal factors and (2) controlled experiments are harder to do in epidemiology.
If...
How much confidence do you place in the scientific theory that ordinary matter is made of discrete units, or 'atoms', as opposed to being infinitely divisible?
More than 50%? 90%? 99%? 99.9%? 99.99%? 99.999%? More? If so, how much more? (If describing your answer in percentages is cumbersome, then feel free to use the logarithmic scale of decibans, where 10 decibans corresponds to 90% confidence, 20 to 99%, 30 to 99.9%, etc.)
This question freely acknowledges that there are aspects of physics which the atomic theory does not directly cover, such as conditions of extremely high energy. This question is primarily concerned with that portion of physics in which the atomic theory makes testable predictions.
This question also freely acknowledges that its current phrasing and presentation may not be the best possible to elicit answers from the LessWrong community, and will be happy to accept suggestions for improvement.
Edit: By 'atomic theory', this question refers to the century-plus-old theory. A reasonably accurate rewording is: "Do you believe 'H2O' is a meaningful description of water?".