What are traditional association studies primarily used for?

Traditional association studies, particularly genome-wide association studies (GWAS), are primarily employed to examine genetic variants that are associated with certain phenotypes or diseases. This method is particularly useful for identifying genetic changes that may have small effects on a phenotype, which might not be detectable without a large sample size due to their subtle influence.

These studies typically focus on identifying common genetic variations across populations and determining whether these variations correlate with specific traits or conditions, even when each variant contributes only a small increment to the overall risk or expression of the trait. By doing so, researchers can gain insights into the underlying genetic architecture of complex diseases, recognizing patterns that are indicative of genetic susceptibility influenced by numerous variants.

The other options do not align as closely with the primary aim of traditional association studies. While genetic overlap can be indicative in some research, it is not the main goal of traditional studies. Similarly, assessing environmental factors and establishing causal relationships are beyond the scope of straightforward association studies, which focus primarily on genetic associations without delving deeply into causal inference or environmental contributions.