Chapter 3: Supply and Demand

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Welcome to the Deep Dive.

We're your shortcut to getting up to speed on complex topics, hopefully with a few interesting facts along the way.

And today we are really diving into the absolute bedrock of economics,

supply and demand.

Exactly.

Our mission here is pretty clear.

We want to equip you with those core principles, drawing from sources like Krugman and Wells' microeconomics that really explain how markets tick in the real world.

Which is, let's face it, crucial stuff, whether you're taking an economics course or just trying to figure out why prices change.

Right.

So let's kick off with a real roller coaster story.

Carnes County,

between about 2010 and 2018, it went through this wild boom, then a bust, then a recovery.

All driven by natural gas and this technology called fracking.

Think about this.

Back in 2002, natural gas was like $2 a unit.

By 2006,

nearly $14.

Quite droopled.

So what drove that?

Two big things, really.

Yeah.

First, the U .S.

economy was rebounding, so demand went up.

And second, Hurricane Katrina hit the Gulf Coast production hard, so supply tightened up.

High demand, less supply.

Classic recipe for soaring prices.

But then things flipped dramatically.

By 2013, prices crashed back down under $2.

And this time it wasn't a slow economy with technology, right?

Exactly.

Fracking check just exploded.

Between 2010 and 2012, U .S.

shale gas production basically doubled.

We ended up the world's biggest producer by 2018.

Okay, so massive increase in supply.

You'd think prices would just stay low forever.

You would, but they didn't.

By 2018, they'd climb back to around $3 .15, even with all that extra gas around.

How did that happen?

Demand caught up again.

Power plants switched from coal, people switched from heating oil, and the U .S.

started exporting a ton of natural gas globally.

So prices up, then down, then back up again.

It's a perfect illustration of this constant dance between supply and demand.

It really is.

And understanding the model behind it is what this deep dive is all about.

We're going to break down that model step by step so you can use it to understand almost any market you look at.

It's foundational for your coursework.

Okay, so foundation level.

Let's start with the absolute basic.

What is a market?

At its simplest, it's just a group of producers and consumers getting together to exchange some good or service.

Think farmers markets, the stock exchange, online platforms.

Got it.

And you mentioned we're focusing on a specific type.

Yes, competitive markets.

The key idea here is lots of buyers, lots of sellers, and crucially, they're all trading the same good or service,

like identical.

And because there are so many, no single person, buyer or seller can really influence the price.

Exactly.

Think about the huge global market for natural gas.

Even a giant company can't just dictate the price.

Compare that to, say, soft drinks.

Coca -Cola and Pepsi definitely have some power to set their prices.

So why start with competitive markets?

Because they're simpler.

Pretty much.

They're easier to model and understanding them gives us a really solid base before we tackle markets where individual players do have influence.

Makes sense.

And for these competitive markets, the supply and demand model is the key.

It's the core tool.

We're going to unpack five key pieces of it today.

Okay, the supply curve.

Third, what makes those curves shift?

Fourth, market equilibrium where things settle.

And fifth, how that equilibrium changes when those curves inevitably move around.

Right, let's dive into number one, demand.

This is about the consumers, right?

How much they want to buy.

Precisely.

And fundamentally, how much they want depends on the price.

Okay.

How do economists show that?

We start with a demand schedule.

It's basically just a table listing different prices for a good and the quantity consumers would want to buy at each price.

Like a price list and how people would buy.

Kind of, yeah.

And then we plot that data on a graph to get the demand curve.

Picture this.

Vertical axis is price,

say, dollars per British thermal unit or BTU for natural gas.

Horizontal axis is quantity trillions of BTUs.

Okay, I got the picture.

So maybe the schedule says at $3, people demand 10 trillion BTUs.

Plot that point.

At $3 .25, maybe they only want 8 .9 trillion.

Plot that.

At $2 .75, maybe they want 11 .5 trillion.

Plot that one too.

And when you connect those points?

You get a line or a curve that slopes downwards from left to right.

Always.

Always downwards.

Why?

That illustrates the law of demand.

It's a fundamental principle.

Other things being equal, when the price of a good rises, the quantity people demand falls.

Higher price, less buying.

Lower price, more buying.

That feels pretty intuitive, like gasoline.

Perfect example.

Think about Europe versus the U .S.

Glass taxes are much higher in Europe, right?

Prices are often double what they are here.

And the result?

Europeans use way less gas per person.

Less than half, actually.

They tend to drive smaller, more fuel -efficient cars.

It's the law of demand in action on a massive scale.

Okay, that makes sense.

Now, you mentioned something earlier about distinguishing between different kinds of changes.

Ah, yes.

This is really important.

And honestly, a point where students often get tripped up, it's the difference between a movement along the demand curve and a shift of the demand curve.

Okay, break that down.

Movement first.

A movement along the curve happens only when the price of that specific good changes.

So if the price of natural gas drops from $3 .50 down to $3, we just slide down the existing demand curve to a point where the quantity demanded is higher.

So, price changes, quantity demanded changes, but we're on the same curve.

Exactly.

Now, a shift of the demand curve, that's different.

This happens when some factor other than the goods' own price changes people's willingness to buy.

Like what?

Remember our natural gas story.

Between 2002 and 2006, the economy got stronger, people had more income.

So even if the price of gas stayed at $3, in 2006, people wanted more gas, say $12 trillion BTUs compared to $10 trillion in 2002.

Ah, so at the same price, the quantity changed.

Precisely.

That means the entire demand curve physically moved or shifted to the right.

We draw a whole new curve, D2, further out than the original D1.

And that's what economists mean by an increase in demand, not just buying more because it's cheaper.

Exactly.

An increase in demand is a rightward shift of the whole curve.

A decrease in demand is a leftward shift.

Getting this movement versus shift distinction right is absolutely critical for analyzing markets correctly.

It avoids logical errors.

Okay, crystal clear.

Movement along the curve equals price change.

Shift of the curve, something else changed.

So what are those something else factors?

You said there were five.

Yep, five main ones that shift demand first.

Changes in the prices of related goods or services.

Related goods,

like competitors.

Sometimes we call those substitutes, goods you can use instead of each other,

like heating oil and natural gas.

If the price of heating oil goes up, people might switch to gas.

So the demand for gas increases shifts right.

Or coffee and tea.

Okay, substitutes.

What else?

The opposite are complements.

Goods often used together, think smartphones and apps, or cars and gasoline.

If the price of cars goes way up, fewer people might buy cars, and thus the demand for gasoline might decrease shift left.

Makes sense.

Substitutes move demand in the same direction as the other goods price change.

Compliments move it in the opposite.

What's number two?

Second factor, changes in income.

How much money people have affects what they buy.

Right.

More money, buy more stuff.

Usually, yes.

For most goods, what we call normal goods, demand increases when income rises.

Think restaurant meals, vacations, natural gas, often.

Not always.

Not always.

There are inferior goods.

For these, demand actually decreases when income rises.

The classic example is maybe long -distance bus tickets.

If your income goes up, you might fly instead, so demand for the bus ride falls.

Interesting.

Okay, third factor.

Third, changes in tastes.

Simple enough preferences change.

Fads, cultural shifts.

Think about fashion.

Demand for certain styles comes and goes.

Men's hats apparently fell out of favor after WWII.

That's a shift in tastes decreasing demand.

Okay, fourth.

Fourth, changes in expectations.

What people think will happen in the future affects what they do now, especially about future prices or their own future income.

Like waiting for a sale.

Exactly.

If you expect holiday decorations to be keeper after the holiday, you wait, decreasing demand now.

Or, back to natural gas, if consumers in 2013 thought those low prices were here to stay, they'd be more likely to invest in switching appliances, increasing demand, than compared to when price drops might have seemed temporary.

Got it.

And the last one, number five.

Fifth,

changes in the number of consumers.

This is pretty straightforward.

Each person has their own individual demand curve.

The market demand curve is just the sum of all those individual demands added together horizontally.

So, if more people move into an area or the population grows?

Market demand increases.

More buyers mean the curve shifts to the right.

Fewer buyers, it shifts left.

Okay.

Those five factors, related goods, prices, income, tastes,

expectations, number of consumers, they're what shift the whole demand curve.

That's the list.

And you see these principles applied in practical ways.

Like the traffic example you mentioned.

Yeah.

Think about cities trying to reduce traffic congestion.

They use these demand shifters.

They can try to decrease demand for driving by making substitutes cheaper subsidizing buses or trains.

Or make complements more expensive.

Right.

Like slapping high taxes on parking downtown makes driving less attractive.

And then there's actually charging people to drive.

That's congestion pricing.

London does it.

Stockholm too.

You pay a fee to enter the city center during peak hours.

It directly raises the price of driving then and there.

And does it work?

The evidence suggests it does.

London saw traffic drop significantly, maybe 15 to 25 percent.

Public transport use went up, biking too.

Stockholm saw similar results, plus fewer accidents and better air quality.

It changes behavior by changing the economic calculation.

Fascinating.

Okay.

Quick check then.

Let's try applying this.

Umbrellas on a rainy day, we said that was a shift, right?

Yeah.

Because the rain, an external factor, increased the desire for umbrellas at any price.

Perfect.

Now what about this?

Cruise lines offer big discounts and suddenly lots more people book cruises.

Shift or movement?

Okay.

The price of the cruise itself went down and that caused more people to book.

So that's a movement along the existing demand curve.

Nailed it.

The quantity demanded increased because the price fell.

All right.

I think I've got a handle on the demand side, the consumers.

What about the producers, the supply side?

Right.

Let's look to the other side of the market.

How much are producers willing to sell?

And again, price is the key determinant.

So same tools, a schedule and a curve.

Exactly.

We have a supply schedule, a table showing quantity supplied at different prices, and we graph it to get the supply curve.

Again, price on the vertical axis, quantity on the horizontal.

But this time the curve looks different.

Generally, yes.

Usually the supply curve slopes upward from left to right.

If natural gas producers can get $2 .50, maybe they'll supply 8 trillion BTUs.

But if the price goes up to $3, they're willing to supply more, say 10 trillion.

Why upward?

Because typically producing more costs more, or producers are more willing to for their product.

So higher price, higher quantity supplied.

Okay.

Upward slope.

And I'm guessing there's the same distinction here between movement and shift.

You guessed right.

Absolutely crucial again.

A movement along the supply curve happens only when the goods own price changes.

Price of natural gas goes from $3 to $3 .50.

Producers respond by increasing the quantity supplied from 10 trillion to, say, 11 .2 trillion BTUs.

We just slide up the existing curve.

But a shift to the supply curve is caused by a change in something other than the goods own price that affects producers' willingness or ability to sell.

Think about that fracking technology again.

It made gas extraction cheaper and easier.

So at any given price, they could supply more gas than before.

Exactly.

That improvement in technology shifted the entire supply curve to the right.

A whole new curve, S2, showing more supply at every price level compared to the old curve, S1.

That's an increase in supply.

Okay.

So what factors shift the supply curve?

Another list of five.

You got it.

Five main shifters for supply.

First, changes in input prices.

Inputs are the resources used to make the good.

Like ingredients or raw materials?

Or labor, energy, machinery.

Think about airlines.

Jet fuel is a major input.

If jet fuel prices soar, the cost of providing flights goes up.

Airlines might cut back on routes or flights.

Supply decreases, the curve shifts left.

Okay.

Input costs, second.

Second, changes in the prices of related goods or services in production.

This one's a bit trickier than on the demand side.

How so?

While producers might make goods that are substitutes in production, they can use the same resources to make one or the other.

Think crude oil refiners can produce gasoline or heating oil from it.

So if the price of heating oil jumps way up.

Refiners might decide to make more lead -in oil and less gasoline because heating oil is now more profitable.

So a rise in the price of heating oil could decrease the supply of gasoline, shifts left.

Okay, that's substitutes.

Are there complements too?

Yes, complements in production.

These are goods that are naturally produced together.

Oil and natural gas often come from the same wells.

If the price of oil rises, drillers have more incentive to drill for oil.

And they end up getting more natural gas as a byproduct.

Exactly.

So a rise in the price of oil could actually increase the supply of natural gas.

Shift right.

Okay, substitutes and complements in production.

Third factor.

Third.

Changes in technology.

This one almost always works in one direction.

Better technology usually lowers production costs or increases efficiency.

Like fracking for natural gas or better ways to make computer chips.

Precisely.

Technological advances generally increase supply, shifting the curve to the right.

Fourth factor.

Fourth.

Changes in expectations.

Just like consumers, producers' expectations about the future matter.

Specifically, what they think future prices will be.

So if they think prices will be higher next month.

They might hold back some of their current supply, store it, and plan to sell it later when the price is better.

So an expected future price increase can decrease current supply.

Shift left.

And if they expect prices to fall.

They'll try to sell as much as possible now before the price drops.

So an expected price decrease can increase current supply.

Shift right.

Makes sense.

And number five.

Same as demand.

Pretty much.

Changes in the number of producers.

Just like market demand is the sum of individual demands, the market supply curve is the sum of all the individual firms' supply curves.

So if new companies enter the market.

Market supply increases, shifting the curve right.

If firms exit the market, supply decreases, shifting left.

Okay, let's connect this to a real world example.

Solar panels.

You mentioned their costs plummeted.

Dramatically.

Like 99 % over 40 years.

It's made solar power really competitive.

What drove that supply increase?

Technology was part of it.

A huge part.

Big advances in making the panels more efficient at converting sunlight into electricity.

That's a rightward shift in supply due to technology.

But you said there was another factor related to inputs or producers.

Yeah, it's interesting.

Polysilicon is a key input for solar panels.

Around 2008, its price shot up.

That initially hurt supply.

Okay, but then?

But that super high price acted like a huge signal.

It incentivized a whole bunch of new companies to start producing polysilicon.

So the number of producers for that key input went way up.

Ah, so more polysilicon producers led to?

A massive increase in polysilicon supply, which eventually drove its price back down by around 2014.

Lower input costs for panel makers meant they could supply more panels more cheaply.

So you had both technology and changes related to input sumber of producers pushing the solar panel supply curve rightward.

Wow, cool interplay.

Alright, another quick check on supply shifts versus movements.

If house prices are booming and more people decide to sell their houses, you said that's a movement along the curve because the high price is the direct trigger.

Correct.

Price change causes change in quantity supplied.

Okay, what about this?

Strawberry farmers switch to growing raspberries because raspberry prices have gone up.

What happens to the supply curve for strawberries?

Hmm.

Strawberries and raspberries might be substitutes in production for those farmers.

If raspberry prices rise, farmers shift resources away from strawberries.

So the supply of strawberries would likely decrease.

That's a shift left for the strawberry supply curve.

Got it.

One more.

Wages for fast food workers increased significantly.

Effect on the supply of fast food.

Wages are an input cost.

Higher input costs generally make production less profitable at given price.

So you'd expect the supply of fast food to decrease.

A shift left of the supply curve.

Okay, I think we've got the two sides, demand and supply, laid out pretty well, along with what moves us along the curves versus what shifts them entirely.

Excellent.

Because the next step is bringing them together.

Right.

Where supply meets demand.

This is equilibrium, isn't it?

That's the term.

A competitive market is in equilibrium when the price hits a point where the quantity consumers demand is exactly the same as the quantity producers supply.

The sweet spot.

Exactly.

We call this price the equilibrium price, or sometimes the market clearing price.

And the quantity bought and sold at that price is the equilibrium quantity.

And on our graph, that's just where the demand curve and the supply curve cross.

Precisely.

The intersection point, often labeled E.

If you draw lines from that point over to the price axis and down to the quantity axis, you find the equilibrium price and quantity.

For our natural gas example, maybe that intersection happens at 3 and 10 trillion BTUs.

So at $3, buyers want 10 trillion and sellers offer 10 trillion.

Everyone's happy.

Well, maybe not happy in an emotional sense, but the market is balanced.

No pressure for the price to change at that specific point.

Why do all sales tend to happen at that one equilibrium price in a real market?

In an established competitive market, information flows.

Buyers shop around, sellers see what others are charging.

If a seller tries to charge much more than the equilibrium, buyers will go elsewhere.

If a buyer tries to pay much less, sellers won't sell to them.

Competition pushes everyone towards that single market clearing price.

Okay.

Well, what if the price isn't at equilibrium?

Say it's too high, like natural gas is priced at $3 .50 instead of the $3 equilibrium.

Good question.

At $3 .50, remember, suppliers want to sell more, maybe 11 .2 trillion BTUs, but consumers want to buy less, maybe only 8 .1 trillion BTUs, because the price is high.

So suppliers have a bunch left over they can't sell.

Exactly.

That situation is called a surplus or excess supply.

Here it would be 11 .2 minus 8 .1, which is 3 .1 trillion BTUs of unsold gas.

What happens then?

Do prices just stay high?

Not usually in a competitive market.

Sellers with unsold inventory get antsy.

They'll start cutting prices to attract buyers and clear out their stock.

That downward pressure on price pushes the market back towards the $3 equilibrium.

Okay.

So surplus leads to falling prices.

What about the opposite?

What if the price is too low, say $2 .75?

At $2 .75, the situation reverses.

Consumers love the low price.

Maybe they demand 11 .5 trillion BTUs, but producers aren't thrilled.

Maybe they only want to supply 9 .1 trillion BTUs at that price.

So now buyers want more than sellers are offering.

Right.

This is called a shortage or excess demand.

Here 11 .5 minus 9 .1 equals a 2 .4 trillion BTU shortage.

That happens now.

Frustrated buyers might start offering slightly higher prices to secure the limited supply, or sellers realize they can charge more because demand is so strong.

Either way, there's upward pressure on the price, pushing it back up towards the $3 equilibrium.

So whether there's a surplus or a shortage, the market naturally pushes the price back to that equilibrium point.

That's the core idea.

The equilibrium price is like a magnet.

The market price always tends to move towards it, automatically clearing up surpluses and shortages through the independent actions of buyers and sellers.

It's quite elegant, really.

It is.

And we see this dynamic play out, sometimes controversially, with things like Uber's surge pricing, right?

No, definitely.

Uber tackled a classic shortage problem, finding a taxi when demand spikes,

rainy days, New Year's Eve, stadium letting out.

It used to be almost impossible.

So how does surge pricing fix the shortage?

By letting the price rise, sometimes dramatically, you hear stories of 9 or 10 times the normal fare during a blizzard.

This does two things simultaneously, based on supply and demand.

Okay, what's the first?

The higher price acts as a huge incentive for more drivers to get out on the road.

People who might have stayed home decide it's worth driving now.

That increases supply.

And the second thing?

The higher price also discourages some potential riders.

People who don't urgently need a ride, or have alternatives, might decide it's not worth paying that much.

That reduces quantity demanded.

So more supply, less demand,

the shortage disappears.

Exactly.

The higher price helps balance supply and demand in real time.

It gets more rides happening than would have occurred at the standard price during that peak time.

Of course, people complain about the high cost.

Yeah, price gouging is the term you hear.

Right.

But from an economic perspective, it's the market mechanism working to allocate a scarce resource, rides during peak times, by letting the price adjust.

It's also interesting that sometimes drivers try to coordinate breaks to create a surge, showing they understand the model, too.

Okay, let's try another check.

Imagine a bumper crop of wine grapes way more than usual.

What happens in the market for wine?

Surplus or shortage?

And what happens to the price?

Bumper crop means a big increase in supply.

At the old price, there would be way too much wine.

That's a surplus.

To sell it all, prices would have to fall.

So equilibrium price goes down, equilibrium quantity goes up.

Makes sense.

What about after a hurricane hits a coastal area, damaging many hotels, but also discouraging tourists?

Ooh, tricky.

You have supply decreasing, damaged hotels, and demand decreasing, fewer tourists.

Both curves shift left.

What happens to quantity is predictable, it will definitely fall.

But the price effect is ambiguous.

It depends on which shift is bigger.

If supply falls more than demand, price could rise.

If demand falls more than supply, price could fall.

Right.

Simultaneous shifts are more complex.

They need to tackle those next.

Exactly.

Because in the real world, things rarely sit still.

Curves are always shifting.

So let's look at what happens to the equilibrium, the price and quantity intersection when a curve shifts.

Start simple.

Just one curve moves.

What if demand increases?

Demand curve shifts right.

Maybe because the price of a substitute went up, like heating oil prices rising boosts demand for natural gas.

Visualize the graph.

D1 shifts right to D2.

At the original equilibrium price, now that demand is higher, there's suddenly a shortage quantity demanded exceeds quantity supplied.

And shortages push prices up.

Right.

The price gets bid up.

As the price rises, we move along the unchanged supply curve until we reach a new intersection point with the new demand curve, D2.

So the new equilibrium E2 is?

At a higher price and a higher quantity than the original equilibrium E1.

So an increase in demand leads to a higher P and a higher Q.

And a decrease in demand.

Curve shifts left.

Opposite happens.

Creates a surplus at the old price.

Price falls.

New equilibrium is at a lower price and a lower quantity.

Got it.

Now, what about shifts in supply?

Say supply increases, curve shifts right.

Like our fracking example.

Okay, S1 shifts right to S2.

At the original equilibrium price, now that supply is higher, there's a surplus quantity supplied exceeds quantity demanded.

Surpluses push prices down.

Exactly.

Price falls.

As the price falls, we move along the unchanged demand curve until we hit the new intersection point with S2.

And the new equilibrium.

Is at a lower price but a higher quantity than before.

So an increase in supply leads to a lower P and a higher Q.

And a decrease in supply.

Like Hurricane Katrina knocking out gas production.

Curve shifts left.

Right.

Creates a shortage at the old price.

Price rises.

New equilibrium is at a higher price and a lower quantity.

That's exactly what happened post -Katrina.

Okay, those single shifts seem fairly predictable in terms of price and quantity changes.

But you mentioned the tricky part is when both curves shift at the same time.

Yes, that's very common.

And the outcome depends on the directions and the magnitudes of the shifts.

Let's take the first case.

They shift in opposite directions.

Say demand goes down, shifts left.

And supply goes up, shifts right.

Okay, think about what each shift does to price individually.

Decrease in demand pulls price down.

Increase in supply also pulls price down.

So the price change is predictable.

It's definitely going down.

Yes.

When they shift in opposite directions, the change in price is predictable.

But - The change in quantity isn't.

Exactly.

The change in quantity is ambiguous.

Decrease in demand pulls quantity down.

Increase in supply pushes quantity up.

Which effect wins?

We don't know without knowing how much each curve shifted.

Can you illustrate that?

Imagine demand falls a lot, but supply increases only a little.

The big demand drop dominates, so overall quantity will likely fall.

But if demand falls just a tiny bit and supply increases massively, then the supply effect dominates, and overall quantity could actually rise.

In both cases, though, the price definitely falls.

Okay.

Opposite direction shifts.

Price is predictable.

Quantity is ambiguous.

What about when they shift in the same direction?

Say both demand and supply increase.

Both shift right.

Now flip the logic.

Increase in demand pushes price up.

Increase in supply pushes price down.

So this time the price change is ambiguous.

We don't know if it'll end up higher or lower.

Correct.

But think about quantity.

Increase in demand pushes quantity up.

Increase in supply also pushes quantity up.

So the quantity change is predictable.

It definitely goes up.

Yes.

When supply and demand shift in the same direction, the change in quantity is predictable, but the change in price is ambiguous.

Again, the curve that shifts more will have the bigger impact on the ambiguous variable.

Price in this case.

Okay.

That's a helpful rule.

Same direction shift.

Quantity predictable, price ambiguous.

Opposite direction shift.

Price predictable.

Quantity ambiguous.

That's the takeaway.

And the curve that shifts further usually dictates the direction of the ambiguous change.

Let's apply this.

You mentioned avocados.

Holy guacamole.

Prices went nuts.

What happened there?

A perfect storm, really.

Two simultaneous shifts.

First, a huge increase in demand.

Americans, Europeans, Chinese, everyone suddenly wanted avocados.

Health trend maybe.

So demand curve shifted right.

Okay.

Demand up.

What about supply?

At the same time, there was a decrease in supplies.

California had its smallest harvest in ages due to a heat wave.

Production in Peru and South Africa also fell.

So the supply curve shifted left.

Demand shifts right.

Pushes price up, quantity up.

Supply shifts left.

Pushes price up, quantity down.

They're shifting in opposite directions regarding their quantity effects.

Exactly.

So what's predictable?

The price.

Both shifts pushed the price up.

So predictably, avocado prices soared.

And they did.

What about quantity?

That's ambiguous.

Increase in demand pushes it up.

Decrease in supply pulls it down.

The final quantity bought and sold depends on which shift was bigger.

Precisely.

It's a fantastic real world example of how combining these shifts explains seemingly crazy price movements.

It wasn't just hype.

Fundamental supply and demand were at play.

Okay.

Final check for understanding.

Let's analyze a scenario.

The market for large SUVs.

Gasoline prices fall significantly.

What happens?

Okay.

Market is large SUVs.

Gasoline is a complement to SUVs.

If gas prices fall, the cost of using an SUV goes down.

This should increase the demand for SUVs.

Demand curve shifts right.

Result.

Higher equilibrium price for SUVs.

Higher equilibrium quantity sold.

Perfect.

How about this?

New technology makes recycling paper much cheaper.

What happens in the market for fresh paper made from virgin pulp?

Recycled paper is a substitute for virgin paper.

If recycled paper gets cheaper due to technology, meaning its supply increases shifting right, then some users might switch away from virgin paper.

This would decrease the demand for virgin paper.

Demand curve shifts left.

Result.

Lower price and lower quantity for virgin pulp paper.

Excellent analysis.

So wrapping up, we focused heavily on competitive markets.

Just remind us why they're so foundational.

It really comes down to the simplicity of decision -making for the individual participants.

Think of a single wheat farmer.

They don't really worry about how much wheat they produce affecting the global price.

They just look at the market price and decide if they can make a profit selling more.

It makes modeling their behavior, and thus the market's behavior, much more straightforward.

Unlike, say, a company that's one of only a few major producers where their decisions do impact the market price.

Exactly.

Those non -competitive markets require different, more complex models which build upon the foundation we've laid today.

But this supply and demand framework for competitive markets is incredibly powerful for explaining a vast range of real -world phenomena.

The key takeaway seems to be nailing that difference between moving along a curve due to price and the whole curve shifting due to one of those other factors.

Absolutely.

If you get that distinction, you've unlocked a huge part of economic thinking.

It helps you analyze news headlines, understand business strategy, and, crucially, tackle your economics exams and coursework.

That's our deep dive into the essential mechanics of supply and demand.

Hopefully you feel better equipped to see these forces at work all around you.

Definitely.

And here's something to think about as you go about your day.

Pick a product you use often.

Can you pinpoint anything recently?

News, trends, tech changes that might have shifted its supply or demand curve.

What might that tell you about why its price or how easy it is to find might be changing right now?

Great.

Final thought.

Thanks so much for joining us on the deep dive.

We hope this helps you make sense of the economic world.