Imagine researchers conduct a GWAS and find a particular allele (let's call it "T-allele") of a genetic marker (a SNP) that's associated with height. People who possess the T-allele at this SNP are, on average, taller than those who don't. After analyzing the data, researchers find that the T-allele is associated with an average increase in height of 2 centimeters (cm). In simple terms: If you have the T-allele, you might be, on AVERAGE, 2 cm taller than if you didn't have that allele. This 2 cm is the effect size of the T-allele for height. However, remember that height is influenced by many genetic factors and environmental factors (like nutrition). So, even if you possess the T-allele, it doesn't guarantee you'll be exactly 2 cm taller than if you didn't. It just gives an average measure of the effect of that specific allele.
What is meant by the effect size of an allele? What is the context for that?
Imagine researchers conduct a GWAS and find a particular allele (let's call it "T-allele") of a genetic marker (a SNP) that's associated with height.
People who possess the T-allele at this SNP are, on average, taller than those who don't.
After analyzing the data, researchers find that the T-allele is associated with an average increase in height of 2 centimeters (cm).
In simple terms:
If you have the T-allele, you might be, on AVERAGE, 2 cm taller than if you didn't have that allele. This 2 cm is the effect size of the T-allele for height.
However, remember that height is influenced by many genetic factors and environmental factors (like nutrition). So, even if you possess the T-allele, it doesn't guarantee you'll be exactly 2 cm taller than if you didn't. It just gives an average measure of the effect of that specific allele.