One of the main factors in elasticity is the number of substitutes available to a specific product. If there are lots of substitutes available, then when a firm tries to raise it price, consumers feel like they can substitute to the relatively cheaper product. That's where firms might turn to advertising. If a firm can make you believe that their product is so uniquely special that an alternative just isn't possible, then they're able to make their demand more inelastic.

Find an advertisement for a product (and be sure to include it) that's trying to change it's elasticity. Recall, it needs to do one of the following: Try to make consumers believe that substitution isn't really an option Try to make their product more of a necessity vs a luxury Try to make time an issue such that you have to buy their product sooner than later.