1. Factors of Demand

2. Marginal Cost & Benefit in Demand
The cost of using one more unit of a good or service.
Marginal Benefit
The benefit or satisfaction received from using one more unit of a good or service.
Law of Diminishing marginal utility: the benefit of using an additional unit of a product during a given period will decline.
Example: Glass of lemonade on a hot day.
1st glass is very refreshing. Is the 2nd class as refreshing? 3rd?

3. Demand Curves
Movement vs. Shift
Movement along the curve is because of change in price
Price ↑ = ↓ Quantity Demand
Price ↓ = ↑ Quantity Demand
Shift occurs because of any change other than price.
Raise at work = ↑ Quantity Demanded
Got fired = ↓ Quantity Demand

4. Change/Movement in quantity demanded.
Movement in quantity demanded happen because of a change in price.
We assume that all other factors have not changed, just the price.
Same income, same desire for the good.
Example: Pizza
The price of pizza decreases from $1.00 to $ You will buy more pizza increase in the quantity demanded of pizza.
The decreasing price of a good (pizza) increases your purchasing power.
The price of pizza increases from $1.00 to $2.00. You will buy less pizza decrease in the quantity demanded of pizza.
The rising price of a good (pizza) diminishes/decreases your purchasing power.

5. Shift in quantity demanded
A shift in demand occurs when we no longer hold other things (changes in your income, change in your tastes/style/fads, the price of substitute goods, etc.) constant.
Shifts occur for any reason other than price.
Example: Candy. You love candy, but you just got fired from your job.
Your QD for candy decreases and shifts downward.
6 different reasons for shifting demand