More on Salsa and Ketchup

Yesterday I posted a link to a story about how salsa has become more popular than ketchup and asked what factors might are more responsible--demand side factors or supply side factors?

My guess is that its mostly demand side. Here are a few for illustration:

1. Tastes of Americans have changed to have more appreciation for spicy food
2. The number of Hispanic Americans continues to grow and they consume more salsa than the average American most likely

There are a number of supply side factors that could be relevant but I don't think they had a major impact.

1. price of tomatoes - lower prices would lead to an increase in supply for both ketchup and salsa since they are both made with tomatoes, but that doesn't help explain why the consumption of sales rose more than for ketchup

2. price of corn - the price of corn has increase dramatically recently, but corn is a key ingredient in almost everything Americas eat. Corn syrup is the main ingredient in ketchup (I think), beef, a complement for both salsa and ketchup, is mostly feed corn, and of course tortilla and chips are strong complements of sales and are made with corn. So corn prices would tend to reduce consumption of both goods.

Salsa more popular than ketchup

Salsa and tortillas are now more popular than ketchup and hamburger buns in the United States.

What is more likely to be driving these changes: demand side factors or supply side factors?

Why does CBS advertise on CBS?

CBS airs a lot of commercials for its own shows. Why?

At first this doesn't seem like a puzzle. Why not? They don't have to pay for it!

But every minute of air time they dedicate to their own commercials is a minute they can't sell to customers. The opportunity cost of advertising their own shows is probably substantial.

In fact, if the TV advertising industry were perfectly competitive then CBS should pay the same price to advertise on its own network (with a cost of MC) as to advertise on NBC (for price P) since P = MC.

Does the same argument hold up if broadcast TV was monopolistically competitive? Can you explain how CBS gains from filling time with its own advertisements?

P.S. Do cable channels advertise their own shows as heavily as broadcast channels do? I don't pay enough attention to notice but why might we expect cable to be more competitive? Why might we expect the opposite?

Complements or Substitutes?

Are the New York Times and the Wall Street Journal substitutes or complements?

I would have thought they were substitutes. They mostly report the same news. Right?

Wrong.