Demand Defined

• Demand: The Different Quantities Of Goods That Consumers Are willing And able To Buy At Different Prices

  • Eg. You Are able To Purchase Diapers, But If You Aren’t willing To Buy, There Is No Demand.

• Law Of Demand: There Is An Inverse Relationship Between Price And Quantity Demanded

  • Result Of Three Separate Behavior Patterns That Overlap

    • Substitution Effect: If The Price Goes Up For A Product, Consumers Buy Less Of That Product And More Of Another Substitute Product (and Vise-versa)

    • Income Effect: If The Price Goes Down For A Product, The Purchasing Power Increases For Customers, Allowing Them To Purchase More

    • Law Of Diminishing Marginal Utility: As You Consume Anything, The Additional Satisfaction That You Receive Will Eventually Start To Decrease

      • Utility = Satisfaction → We Buy Goods To Get Utility From Them

      • The More You Buy Of Any Good, The Less Satisfaction You Get From Each New Unit Consumed

Graphing Demand

• Demand Curve: A Graphical Representation Of A Demand Schedule

  • Downward Sloping, Showing The Inverse Relationship Between Price (on The Y-axis) And Quantity Demanded (on The X-axis)

  • When Reading A Demand Curve, Assume That All Outside Factors Such As Income Are Held Constant → “ceteris Paribus”

Shifts In Demand

• Ceteris Paribus: All Other Things Held Constant

  • When This Assumption Is Dropped, Movement No Longer Occurs Along The Demand Curve; Rather, The Entire Demand Curve Shifts

  • A Shift Means That At The Same Prices, More People Are Willing And Able To Purchase That Good

  • This Is A Change In Demand, Not A Change In Quantity Demanded → Price Doesn’t Shift The Curve!!

• What Causes Shifts In Demand? 5 Shifters [determinants] Of Demand

  1. Tastes And Preferences

  2. Number Of Consumers

  3. Price Of Related Goods

     • The Demand Curve Of One Good Can Be Effected By A Change In The Price Of Another Related Good

       • substitutes: Goods Used In Place Of One Another

         • If The Price Of One Increases, The Demand For The Other Will Increase (or Vise Versa)

         • Eg. If The Price Of Pepsi Falls, Demand For Coke Will Fall

       • complements: Two Goods That Are Bought And Used Together

         • If The Price Of One Increases, The Demand For The Other Will Fall (or Vise Versa)

         • Eg. If The Price Of Hot Dogs Falls, Demand For Hot Dog Buns Will Increase

  4. Income

     • The Incomes Of Consumers Change The Demand, But How Depends On The Type Of Good

       • Normal Goods — As Income Increases, Demand Increases +v/v

         • Eg. Luxury Cars, Seafood, Jewelry, Homes

       • Inferior Goods — As Income Increases, Demand Falls +v/v

         • Eg. Top Ramen, Used Cars

  5. Future Expectations

• Changes In Price Don’t Shift The Curve, They Only Cause Movement Along The Curve.

Price Elasticity Of Demand

• Law Of Demand — Consumers Will Buy More When Prices Go Down And Less When Prices Go Up

  • elasticity: The Concept Of Determining How Much More/less

• price Elasticity Of Demand (PED): Measurement Of How Sensitive Quantity Demanded Is To A Change In Price

  • Knowing How Consumers Will Respond To A Change In Price Is Extremely Useful To Firms

    • Helps Decide What To Charge, When/if To Have Sales

    • Helps Determine How Many Substitutes Are In The Market

  • Used By Government To Decide When & How Much To Tax

• Elasticity Varies Along A Linear Demand Curve; Elasticity Is Not Slope

Elastic And Inelastic Demand

Elastic Demand

• Elastic Demand: When A Quantity Is Sensitive To A Change In Price

  • If Price Increases, Quantity Demanded Will Fall A Lot

  • If Price Decreases, Quantity Demanded Will Rise A Lot

  • The Amount People Buy Is Sensitive To Changes In Price

  • Elastic Demand Curve Is Flat

  • General Characteristics Of Elastic Goods

    • Many Substitutes

    • Luxury Goods

    • Large Portion Of Income

    • Plenty Of Time To Decide On Purchases

    • Elasticity Coefficient Greater Than One

Inelastic Demand

• Inelastic Demand: When A Quantity Is Insensitive To A Change In Price

  • If Price Increases, Quantity Demanded Will Fall A Little

  • If Price Decreases, Quantity Demanded Will Rise A Little

  • People Will Continue To Buy Regardless Of Changes In Price

  • Inelastic Demand Curve Is Steep

  • General Characteristics Of Inelastic Goods

    • Few Substitutes

    • Necessities

    • Small Portion Of Income

    • Required Immediately Rather Than Later

    • Elasticity Coefficient Less Than One

Calculating Percent Change

• % Change = [(new #-old #)/(old #)] X 100

Total Revenue Test

• Total Revenue Test: Test That Uses Elasticity To Show How Changes In Price Will Affect Total Revenue (TR)

  • Elastic Demand — Price Increase = TR Decrease +v/v

  • Inelastic Demand — Price Increase = TR Increase +v/v

  • Unit Elastic — Price Changes, TR Remains Constant