Okay, So hello and welcome everyone. My name is Ben Zamzow and I'm going to do a walkthrough on the estimating elasticities assignment. So the first thing actually, as you're starting this, as you're looking through this, is to take to heart the basic application of the definition of elasticity, which is that we want to find the effect of a change in one variable on another variable. Elasticities are all about responsiveness. And to be able to identify that effect, we have to be clear. We have to be sure that that effect is only coming through one channel