Economics: supply and demand

I have been listening to Economics, a lecture series by Professor Timothy Taylor. I am learning quite a few new ideas from it. Going to write them down here on my blog so I have someplace to review them later if/when I need to.

• When price goes up, units supplied goes up. When price goes down, units supplied goes down, too. Because when the price is more, suppliers can make more money from sale.
• When price goes up, units demanded goes down. Likewise, when price goes down units demanded goes up.
• When price is too low or too high, market moves the price to a state where units supplied is equal to units demanded. This state is known as equilibrium. Market always moves toward equilibrium.
• Attempts to arbitrarily move price away from equilibrium — such as setting a price ceiling or price floor will very likely fail. That’s just how market works.
• Elasticity of demand (or supply) specifies how much demand (or supply) can change when price changes by a specified amount.
• If demand for a certain product is elastic, it means changing the price will affect how much it is demanded in the market. Demand (or supply) for some products are elastic in any given market, or inelastic. What’s elastic in one market may not be elastic in a different market, or in the same market at a different time. When fixing prices, a firm should consider if the demand is elastic or not.