Final answer:
Observational studies establish correlations but not causations due to the inability to control for confounding variables. They show associations between variables but cannot confirm that one variable causes another to change.
Step-by-step explanation:
Observational studies typically point out correlations between aspects of the natural world but do not establish solid cause-effect relationships.
Observational studies are designed to observe and record events or characteristics in their natural setting without the influence of experimental manipulation. They can identify whether there is a correlation between variables but can't conclusively demonstrate that one variable causes another to change. The absence of strict control over variables in observational studies means that researchers cannot rule out the possibility that other, uncontrolled factors, known as confounding variables, might be influencing the observed relationships.
For instance, an observational study may find that individuals who sleep less are more likely to develop heart disease, but without controlling for other factors like stress levels or diet, the study cannot say for certain that reduced sleep is the cause of heart disease.