demand ib economics. demand for chocolate bars experiment

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Page 1: Demand IB Economics. Demand for chocolate bars experiment

Demand

IB Economics

Page 2: Demand IB Economics. Demand for chocolate bars experiment

Demand for chocolate bars experiment

Page 3: Demand IB Economics. Demand for chocolate bars experiment

Getting an idea of what demand isThe demand for chocolate bars experiment

• In my shop I have 4 items for sale

50p50p 50p

50p

Page 4: Demand IB Economics. Demand for chocolate bars experiment

Product Quantities

Can of coke (50p)  

Snickers bar (50p)  

Pint of milk (50p)  

Mars bar (50p)  

Getting an idea of what demand isStage 1

Each item is 50p eachYou have £2.50 to spend and must spend it allYou can buy any number of one product and do not have to buy all of the productsWhen you have made your decision draw a table like the one below and fill it out

Page 5: Demand IB Economics. Demand for chocolate bars experiment

Stage 2 It’s a new day and you have consumed everything that you bought

yesterday A global shortage of peanuts has put the price up of a snickers bar

to £1

50p50p 50p

£1

Page 6: Demand IB Economics. Demand for chocolate bars experiment

Product Quantities

Can of coke (50p)  

Snickers bar (£1)  

Pint of milk (50p)  

Mars bar (50p)  

Demand for chocolate bars experiment continuedStage 2

It’s a new day and you have consumed everything that you bought yesterdayA global shortage of peanuts has put the price up of a snickers bar to £1You still have £2.50 income to spend and must spend it allYou can buy any number of one product and do not have to buy all of the productsWhen you have made your decision draw a table like the one below again and fill it out with your new preferences

Page 7: Demand IB Economics. Demand for chocolate bars experiment

Demand for chocolate bars experiment continuedStage 3 – calculating market demand

Organise yourself into a groupWork out the market quantities for your group for stages 1 and 2. Do this by adding together the quantities for each product at each price level demanded by each person in your group. See an example below

ProductQuantities - Stage 1(Snickers cost 50p)

Quantities - Stage 2(Snickers cost £1)

Can of coke ||||| ||||| |||| 14 ||||| |||| 9

Snickers bar ||||| ||||| ||| 13 |||| 4

Pint of milk ||||| ||||| || 12 ||| 3

Mars bar ||||| ||||| ||||| |||| 19 ||||| ||||| |||| 14

What this represents is the demand for each product – the amount each person would like to purchase at the price stated. By adding together each individual’s demand we get the market demandMake your team a table like the one above and complete it

Page 8: Demand IB Economics. Demand for chocolate bars experiment

Demand for chocolate bars experiment continuedStage 3 – calculating market demand

Now lets represent this information in the form of a graphUse the graph paper providedPrice goes on the vertical axisQuantity demanded goes on the horizontal axisPlot the quantity demanded of snickers bars for your group against the price (see the example below)You will see two points on the graph – one for the quantity demanded at 50p and another for the quantity demanded at £1Draw these two points and draw a straight line through them like below

Page 9: Demand IB Economics. Demand for chocolate bars experiment

Demand for chocolate bars experiment continuedStage 3 – calculating market demand

Now compare your graph with the other group’s graphAre they the same shape?Do they both slope downwards from left to right?So what can you conclude about the relationship between price and the amount demanded?

Use your graph to estimate the following for your groupWhat is the demand likely to be if the price were 75p? What is the demand likely to be if the price were 25p?What is the demand likely to be if the price were 60p?

Page 10: Demand IB Economics. Demand for chocolate bars experiment

Demand for chocolate bars experiment continuedLet's now take the game one step further.

Stage 4It is now day three and the peanut crisis has eased. Snickers now cost 50p once more. The government has decided to provide all students with a grant

As a result your income has increased and you now have £4 to spend. Again, in your group work out market demand by adding together each person's demand for each productThe rules are the same as beforeFill out your individual table to find your individual demandFill out your group table to find your market demand (the sum of all your individual demands)Then create a table like the one below

ProductQuantities - Stage 1

(Income is £2.50)Quantities - Stage 4

(Income is £4)

Can of coke    

Snickers bar    

Pint of milk    

Mars bar    

Page 11: Demand IB Economics. Demand for chocolate bars experiment

Demand for chocolate bars experiment continuedStage 4 continuedComparing stage 1 and stage 4 what can we see?Was the demand for all of the goods greater than before?This is because demand is not static – it changes as a result of changes in factors that affect demand (other than price)So we know now that one of these factors is income; we saw that when we had an increase in income our demand levels increased.What other factors might increase demand? What factors might decrease demand?On your original graph plot the new snickers demand.Assume that you would get the same increase in demand at £1 and plot your second point.Now draw your new demand line What do we see?

Now lets have a look at the theory of demand

Page 12: Demand IB Economics. Demand for chocolate bars experiment

The Theory of Demand

Page 13: Demand IB Economics. Demand for chocolate bars experiment

Quantity Demanded

Demand

P1

Q1 Q3Q2

P2

P3

Price

The Demand CurveOften we desire certain things like luxury cars or jewellery but we don’t have the ability to buy them so they are not a part of what economist consider demandDemand is the amount that consumers are willing and able to buy at each given price levelThis is what we call effective demand because it is backed by purchasing powerThe demand curve illustrates the relationship between the price and the amount consumers intend to buy at each given price (note the word intend – demand diagrams show planned or intended spend not realised or actual demand)We can see that there is an inverse or negative relationship – as the price goes up the demand goes downNote also the notation that we use

Demand Curve

Remember……Demand goes Down!!!

Watch this video

Page 14: Demand IB Economics. Demand for chocolate bars experiment

Drawing diagramsIt is really important that you learn to draw the diagrams well because there are a lot of marks to gain if you do it correctlyUse a ruler and a sharp pencilLabel the axes properly (quantity always goes on the x axis and price on the y when we draw demand diagrams)If you were illustrating a certain market e.g. cars you would write Quantity of cars or price of carsWe draw demand curves as a straight lineWe can draw several curves on one diagram but we have to label them each differently

The first demand curve we drew would be labelled D1 The first demand curve we drew would be labelled D2

We label the prices and the quantities on the axis in the same wayWe always draw the curve first and then draw the dotted lines to show the new prices and quantitiesLater you will shade parts of diagrams and it is good to have different colours (pencil only) to hand although in the exam you will only have black Diagrams must be large enough so that labels can be seen clearlyYou MUST always explain/analyse what is happening in a diagram. This is why it is good to use different colours because you can use the colour to describe the area or line you are discussing.

I WILL GIVE YOU A HARD TIME IF YOU DRAW SMALL AND MESSY DIAGRAMS!!!!!!!

Page 15: Demand IB Economics. Demand for chocolate bars experiment

The individual demand curve for a good and market demandEach consumer will buy as much of a product they deem as worth it at each given price levelA demand curve can be plotted for each individual To identify the market demand we calculate the sum of the demand from all individualsBelow individual 1 buys 3 cans of coke, individual 2 buys 2 cans of coke and so the overall demand or the market demand is 2+3 = 5This is exactly what you did with the demand for snickers. You worked out your individual demand and then the group (market) demand

Quantity

D

50p

5

Price

Quantity

D

50p

3 Quantity

D

50p

2

PricePrice

Individual demand 1 Market DemandIndividual demand 1

Demand curves for coke

Page 16: Demand IB Economics. Demand for chocolate bars experiment

The shape of demand curvesAs we have already said the demand curve typically slopes down from left to right There is a negative relationship between price and quantityThis is because of the assumptions we make about consumersThey want to maximise the benefits they can receive with their limited incomeThey will only buy something if they feel it is worth itThe benefits from buying it have to outweigh the opportunity cost of using the money for something elseThis is what we call rational behaviour – it would be irrational to buy something that we didn’t think was worth it!!The law of economics says that as we buy more and more of something the benefit we get from each extra unit will fallthink about if you bought a cake and ate it, bought another and ate it, bought another and ate it…each time the cake would be less appealing and eventually you might not want to buy any at all!This is true with all products although the point at which the value falls will depend on the person and the productSo, the point is..

As we buy more it becomes less valuable which means we will only buy more if the price falls (it has to be worth it!) – hence the downward sloping curve.

Page 17: Demand IB Economics. Demand for chocolate bars experiment

Movements along the demand curvesWhen there is a change in price there is a movement along the demand curveWhen there is a fall in price there is an extension in demand (demand grows because the price is less and it is worth buying more)There is a movement down the curve (there is an increase in the quantity demanded)When there is an increase in price there is a contraction in demand (because the price is more it becomes less valuable and we buy less)There is a movement up the curve (there is a decrease in the quantity demanded)Remember – movements along the curve are always caused by a change in price – nothing else!!!!

Important wording!

Page 18: Demand IB Economics. Demand for chocolate bars experiment

A contraction of demand

Quantity Demanded

D

P1

Q1Q2

P2A contraction of demand

due to a higher price

Price

How to describe this?

At the original price P1 there is a demand for the quantity Q1. As the price increases to P2 consumers see less value in the product and demand less. There is a contraction of demand and the quantity demanded reduces to Q2. Note: I talk about 1) where we were to start with, then 2) where we have got to and why that has happened.

0

Page 19: Demand IB Economics. Demand for chocolate bars experiment

Time for you to draw!

Answer:

1.Describe the starting point

2.Describe the change

3.Describe what is happening in the diagram

At the original price P1 there is a demand for the quantity Q1 of strawberries.

As the price increases to P2 consumers see less value in the strawberries and demand less.

There is a contraction of demand and the quantity demanded reduces to Q2.

Quantity Demanded

D

P1

Q1Q2

P2A contraction of demand

due to a higher price

Price

0

In the market for strawberries there has been an increase in priceDraw the diagram and analyse (describe what is happening)

Page 20: Demand IB Economics. Demand for chocolate bars experiment

Time for you to draw!

Answer:

1.Describe the starting point

2.Describe the change

3.Describe what is happening in the diagram

At the original price P1 there is a demand for the quantity Q1 of copper.

As the price increases to P2 consumers see less value in the copper and demand less.

There is a contraction of demand and the quantity demanded reduces to Q2.

Quantity Demanded

D

P1

Q1Q2

P2A contraction of demand

due to a higher price

Price

0

In the market for copper there has been an increase in priceDraw the diagram and analyse (describe what is happening)

Page 21: Demand IB Economics. Demand for chocolate bars experiment

An extension of demandHow to describe this?

At the original price P1 there is a demand for the quantity Q1. As the price decreases to P2 consumers see more value in the product and demand more. There is an extension of demand and the quantity demanded increases to Q2. Note: I talk about 1) where we were to start with, then 2) where we have got to and why that has happened.

Quantity Demanded

Demand

P1

Q1 Q2

P2

An extension of demand due to a lower price

Price

0

Page 22: Demand IB Economics. Demand for chocolate bars experiment

Time for you to draw!

Answer:

1.Describe the starting point

2.Describe the change

3.Describe what is happening in the diagram

At the original price P1 there is a demand for the quantity Q1 of gold.

As the price decreases to P2 consumers see more value in the gold and demand more.

There is an extension of demand and the quantity demanded increases to Q2.

In the market for gold there has been a decrease in priceDraw the diagram and analyse (describe what is happening)

Quantity Demanded

Demand

P1

Q1 Q2

P2

An extension of demand due to a lower price

Price

0

Page 23: Demand IB Economics. Demand for chocolate bars experiment

Shifts of the demand curvesWhen we did our Snickers experiment we saw that an increase income made us buy more at the same price.When we drew the 2nd curve we saw that it had moved outwardsWhat makes someone want to buy more of something at the same price?Think about a holiday in a villa in Spain - why would there be more demand for this even though the price had not changed?

Income – if average incomes rise demand may riseCost of flights – if the cost went down more people may consider - complementary goodsOther European holidays become more expensive – the villa in Spain would be more attractive. The other European holidays would be known as a substitute

substitutes – a competing alternative

Complementary goods – goods that are consumed together e.g. DVDs and DVD players

Page 24: Demand IB Economics. Demand for chocolate bars experiment

Shifts of the demand curvesThings that cause a shift of the demand curve (and none of those are price!!) are called determinants of demandPrices of complements (things you buy with that product) e.g. ink cartridges with printersAdvertising and branding that creates desire and loyalty for a productTrends/FashionPrice – not a determinant!Income level – this is the most importantprices of substitutes (similar products) e.g. Xbox and playstation are substitutesRemember CATPIS!!

Watch this video

Page 25: Demand IB Economics. Demand for chocolate bars experiment

Shifts in Demand

How to describe this?This diagram shows how there has been an increase in demand at the same price (P1). The demand curve has shifted from D1 to D2 because there has been ______ (fill this blank with - an increase in income, or increase in substitute price, or decrease in complementary price or whatever the reason). This factor has made the consumers think that the product is more valuable at price P1 and therefore they want to buy more. The original quantity demanded was Q1 and the new quantity demanded is higher at Q2. There is an increase in demand for every given price level

Price

Quantity Demanded

D1

P1

Q1 Q2

D2

Increase in Demand

0

The curve moves to the Right so the demand is

moRe

The shift of the demand curve to the right means that there is more demand at every given price level. This is called a change in demand (not a change in quantity demanded like before)

Page 26: Demand IB Economics. Demand for chocolate bars experiment

Time for you to draw and write an explanation

In the market for strawberries there has been a medical journal published that says strawberries prevent cancer.

Draw a diagram and analyse

Shifts in Demand

Analysis1.Describe the starting point. At P1…..2.Describe what has happened (what happens when this journal is published)3.Describe what has happened to the demand curve

1.At P1 the quantity of strawberries demanded is Q1.2.Due to the fact that strawberries are seen as a cancer preventing agent there will be an increase in demand for strawberries3.The demand curve shifts outwards from D1 to D2 and the quantity demanded increases to Q2

Price

Quantity Demanded

D1

P1

Q1 Q2

D2

Increase in Demand

0

The curve moves to the Right so the demand is

moRe

Page 27: Demand IB Economics. Demand for chocolate bars experiment

Time for you to draw and write an explanation

In China there is a massive increase in demand for washing machines. Copper is used to create the electrical wires. What happens in the market for copper?

Shifts in Demand

Analysis1.Describe the starting point. At P1…..2.Describe what has happened (change in demand for washing machines)3.Describe what has happened to the demand curve

1.At P1 the quantity of copper demanded is Q1.2.Due to the fact that there is an increased demand for washing machines there is an increase in demand for copper.3.The demand curve shifts outwards from D1 to D2 and the quantity demanded increases to Q2

Price

Quantity Demanded

D1

P1

Q1 Q2

D2

Increase in Demand

0

The curve moves to the Right so the demand is

moRe

Draw a diagram and analyse

Page 28: Demand IB Economics. Demand for chocolate bars experiment

Shifts in DemandHow to describe this?This diagram shows how there has been a decrease in demand at the same price (P1). The demand curve has shifted from D1 to D2 because there has been ______ (fill this blank with – a fall in incomes, or decrease in substitute price, or increase in complementary price or whatever the reason). This factor has made the consumers think that the product is less valuable at price P1 and therefore they want to buy less. The original quantity demanded was Q1 and the new quantity demanded is lower at Q2. There is a decrease in demand at every given price.

Quantity Demanded

D1

P1

Q1Q2

D2

Decrease in Demand

Price

0

The shift of the demand curve to the left means that there is less demand at every given price level

The curve moves to the Left so the demand is

Less

Page 29: Demand IB Economics. Demand for chocolate bars experiment

Time for you to draw and write an explanation

The government has just banned smoking inside public buildings. Describe the effect on the market for cigarettes

Shifts in Demand

Analysis1.Describe the starting point. At P1…..2.Describe what has happened (ban)3.Describe what has happened to the demand curve

1.At P1 the quantity of cigarettes demanded is Q1.2.Due to the change in law there is less demand for cigarettes 3.The demand curve shifts inwards from D1 to D2 and the quantity demanded reduces to Q2

Draw a diagram and analyse

Quantity Demanded

D1

P1

Q1Q2

D2

Decrease in Demand

0

The curve moves to the Left so the demand is

Less

Page 30: Demand IB Economics. Demand for chocolate bars experiment

Time for you to draw and write an explanation

The government has launched an advertising campaign to show the negative effects of too much sugar in your diet. What will happen to the sugar market?

Shifts in Demand

Analysis1.Describe the starting point. At P1…..2.Describe what has happened (advert)3.Describe what has happened to the demand curve

1.At P1 the quantity of sugar demanded is Q1.2.Due to the advertising campaign there is less demand for sugar3.The demand curve shifts inwards from D1 to D2 and the quantity demanded reduces to Q2

Draw a diagram and analyse

Quantity Demanded

D1

P1

Q1Q2

D2

Decrease in Demand

0

The curve moves to the Left so the demand is

Less

Page 31: Demand IB Economics. Demand for chocolate bars experiment

Normal and Inferior Goods When we say that as income rises the

demand for a good will increase we are making an assumption that the good we are discussing is a normal good

For normal products, more is demanded as income rises, and less as income falls

There are exceptions called inferior goods They are often cheaper poorer quality

substitutes for some other good With a higher income a consumer can

switch from the cheaper substitute to preferred alternative

As a result, less of the inferior product is demanded at higher levels of income

An example is cheap bread in developed countries or rice in developing countries

Normal good – more is demanded when income rises

Inferior good – less is demanded when income rises

Page 32: Demand IB Economics. Demand for chocolate bars experiment

Does it look Shifty?

Price of Tennis Balls

Here are some scenarios. On your mini white boards draw the change•The price of tennis balls falls•The price of tennis rackets goes up•It is anticipated that tennis balls will go down in price in the next few months•Slazenger, Adidas and Dunlop start advertising campaigns for their sports equipment•The population of Glasgow increases•There are no British success stories at Wimbledon for years and years•Average incomes in Glasgow rise•The price of tennis balls goes up•Cricket becomes cheaper to play and more fashionable as a summer activity

Market for Tennis Balls in Glasgow

Mind your P’s and Q’s!!

Page 33: Demand IB Economics. Demand for chocolate bars experiment

Composite Demand There are a couple of types of demand

that you need to know about other than effective demand. The first is Composite Demand and the second is Derived Demand

Wheat is used for pasta It is also used for biofuel With global warming and the need to find

more efficient fuels biofuel is increasing in demand

As the demand for biofuel increase so does the increase in demand for wheat (derived demand)

Wheat is needed for both pasta and biofuel (composite demand)

As demand increases for wheat the price goes up

The price goes up for pasta and biofuel

2007 - Italian pasta manufacturers have warned that the price of pasta, one of Italy's staple foods, will go up by about 20% this autumn. Global warming and the growing use of durum wheat as a bio-fuel are blamed.

Composite demand – a good that is demanded for more than one use – if there is an increase in one this could lead to a shortage in the other and a higher price

Derived demand is when the demand for one good or service comes from the demand for another good or service

Page 34: Demand IB Economics. Demand for chocolate bars experiment

Derived demand

The housing market is a good example of the idea of derived demand. When construction of new homes rises, so too does the demand for materials used in new properties as well as demand for labour

Other examples

An increase in demand for healthcare will lead to an increase in demand for doctors

An decrease in demand for cars will lead to a decrease in demand for steel

Growth in global economic output will lead to an increase in the demand for oil

Derived demand is when the demand for one good or service comes from the demand for another good or service

Page 35: Demand IB Economics. Demand for chocolate bars experiment

Important to remember…When we talk about market forces (supply and demand) we are assuming that the market is perfectly competitive

there are lots of small firms that have no price making power firms are price takers – they have to take their price from the market

The market price comes about because of supply and demand (market forces)There is an invisible hand that sets the market price (Adam Smith)When you are describing a change in a market the change in demand comes first and the price changes as a result (not the other way around) More about this later……

Adam Smith

Adam Smith

Page 36: Demand IB Economics. Demand for chocolate bars experiment

Consumer SurplusConsumer surplus is a measure of welfare gained as a result of consuming goods and services

Watch this pajholden videohttp://www.youtube.com/watch?v=qTxniCLYgok

Page 37: Demand IB Economics. Demand for chocolate bars experiment

Starter from Easy Mark Qs

Page 38: Demand IB Economics. Demand for chocolate bars experiment

Complete the following 2 questions Remember to include

Definition/s Diagram/s Analysis (description of what is happening

and the changes in the diagram)get your wording right (look at the

previous slides)Label the diagram and refer to it e.g. “in

figure 1 demand has……” Example

1. Distinguish between a shift of the demand curve for a product and a movement along the product’s demand curve

2. With reference to two different determinants of demand explain why the demand for bicycles might increase

Page 39: Demand IB Economics. Demand for chocolate bars experiment

The HL Bit!

Page 40: Demand IB Economics. Demand for chocolate bars experiment

Linear Demand FunctionsWe can show the relationship between the demand for a product and individual determinants of demand by using an equationThis is the demand functionA simple demand function relating the quantity demanded of a product to the price of the product is usually shown in this formQD = a – bPQD is the quantity demandedP is the pricea is the quantity that would be demanded if the price was zerob is the slope of the curveRead through page 25/26 from the 4th paragraph - an example of such…..Complete the student workpoint 2.2 on page 27

QD = a – bP

Quantity demanded if price is zero

The slope of the curve

The price

Quantity demanded