Question

In this question, I am confused about the difference between correlation and concordance. Can somebody explain this to me?

1. Consider the following scenario, and briefly describe what the correlations say about the relative genetic and environmental influences for the trait in question. You decide to conduct a follow-up study on tattoo and piercing behavior using a slightly different experimental design. This time, you collect data on the number of tattoos and piercings between monozygotic twins who were either raised apart OR raised together. You find that there is a 0.8 correlation for monozygotic twins raised together, but there is a 0.2 correlation for monozygotic twins raised apart.

2. Why was “correlation” the proper measurement/terminology to use, not “concordance”?

Answer 1

Correlation means a mutual relationship between the twins,that can change when they are raised apart.There is mental relationship between the twins when they are raised together.They eat ,play,sleep together which create a bond between them.That is why there is a high correlation for the twins raised together.While concordance means that twins both have or both lack at a given trait.When we talk about the health related things it is better to use concordance rather than correlation of the twins.