Zane is examining two studies involving how different generations classify specified items as either luxuries or necessities. In the first study, the Echo generation is defined to be people ages 18–29. The second study defined the Echo generation to be people ages 20–31. Zane notices that the first study was conducted in 2006 while the second one was conducted in 2008.

(a) Are the two studies inconsistent in their description of the Echo generation?

(b) What are the birth years of the Echo generation?