[[Image:Metcalfe-Network-Effect.svg|right|thumb|Diagram illustrating the network effect in a few simple phone networks. The lines represent potential calls between phones. As the number of phones connected to the network grows, the number of potential calls available to each phone grows and increases the utility of each phone, new and existing.]]
In [[economics]], a network effect (also called network externality or demand-side economies of scale) is the phenomenon by which the [[Value (economics)|value]] or [[utility]] a user derives from a good
depends on the number of users of compatible products. Network effects are typically positive, resulting in a given user deriving more value from a product as other users join the same network. The adoption of a product by an additional user can be broken into two effects: an increase in the value to all other users ( "total effect") and also the enhancement of other non-users motivation for using the product ("marginal effect").
Network effects can be direct or indirect. Direct network effects arise when a given user's utility increases with the number of other users of the same product or technology, meaning that adoption of a product by different users is complementary.
This effect is separate from effects related to price, such as a benefit to existing users resulting from price decreases as more users join. Direct network effects can be seen with social networking service
s, including Twitter
, and LinkedIn
s devices like the telephone
; and instant messaging
services such as MSN
. Indirect (or cross-group) network effects arise when there are "at least two different customer groups that are interdependent, and the utility of at least one group grows as the other group(s) grow".
For example, hardware may become more valuable to consumers with the growth of compatible software.
Network effects are commonly mistaken for economies of scale
, which describe decreasing average production costs in relation to the total volume of units produced. Economies of scale are a common phenomenon in traditional industries such as manufacturing, whereas network effects are most prevalent in new economy
industries, particularly information and communication technologies
. Network effects are the demand side
counterpart of economies of scale, as they function by increasing a customer's willingness to pay due rather than decreasing the supplier's average cost.
Upon reaching critical mass, a bandwagon effect
can result. As the network continues to become more valuable with each new adopter, more people are incentivised to adopt, resulting in a positive feedback
loop. Multiple equilibria and market tipping are two key potential outcomes in markets that exhibit network effects. Consumer expectations are key in determining which outcomes will result.
Network effects were a central theme in the arguments of Theodore Vail
, the first post-patent
president of Bell Telephone
, in gaining a monopoly on US telephone services. In 1908, when he presented the concept in Bell's annual report, there were over 4,000 local and regional telephone exchanges, most of which were eventually merged into the Bell System
Network effects were popularized by Robert Metcalfe
, stated as Metcalfe's law
. Metcalfe was one of the co-inventors of Ethernet
and a co-founder of the company 3Com
. In selling the product, Metcalfe argued that customers needed Ethernet cards to grow above a certain critical mass
if they were to reap the benefits of their network. According to Metcalfe, the rationale behind the sale of networking cards was that the cost of the network was directly proportional to the number of cards installed, but the value of the network was proportional to the square of the number of users. This was expressed algebraically as having a cost of N, and a value of N2
. While the actual numbers behind this proposition were never firm, the concept allowed customers to share access to expensive resources like disk drives and printers, send e-mail, and eventually access the Internet.
The economic theory of the network effect was advanced significantly between 1985 and 1995 by researchers Michael L. Katz, Carl Shapiro, Joseph Farrell, and Garth Saloner. Author, high-tech entrepreneur Rod Beckstrom
presented a mathematical model for describing networks that are in a state of positive network effect at BlackHat and Defcon in 2009 and also presented the "inverse network effect" with an economic model for defining it as well. Because of the positive feedback often associated with the network effect, system dynamics
can be used as a modelling method to describe the phenomena. Word of mouth
and the Bass diffusion model
are also potentially applicable.
Adoption and competition
In the early phases of a network technology, incentives to adopt the new technology are low. After a certain number of people have adopted the technology, network effects become significant enough that adoption becomes a dominant strategy
. This point is called critical mass. At the critical mass point, the value obtained from the good or service is greater than or equal to the price paid for the good or service.
When a product reaches critical mass, network effects will drive subsequent growth until a stable balance is reached. Therefore, a key business concern must then be how to attract users prior to reaching critical mass. Critical quality is closely related to consumer expectations, which will be affected by price and quality of products or services, the company's reputation and the growth path of the network.
Thus, one way is to rely on extrinsic motivation, such as a payment, a fee waiver, or a request for friends to sign up. A more natural strategy is to build a system that has enough value ''without'' network effects, at least to early adopters
. Then, as the number of users increases, the system becomes even more valuable and is able to attract a wider user base.
Beyond critical mass, the increasing number of subscribers generally cannot continue indefinitely. After a certain point, most networks become either congested or saturated, stopping future uptake. Congestion occurs due to overuse. The applicable analogy is that of a telephone network. While the number of users is below the congestion point, each additional user adds additional value to every other customer. However, at some point, the addition of an extra user exceeds the capacity of the existing system. After this point, each additional user decreases the value obtained by every other user. In practical terms, each additional user increases the total system load, leading to busy signal
s, the inability to get a dial tone
, and poor customer support
. Assuming the congestion point is below the potential market size, the next critical point is where the value obtained again equals the price paid. The network will cease to grow at this point if system capacity is not improved. Peer-to-peer
(P2P) systems are networks designed to distribute load among their user pool. This theoretically allows P2P networks to scale indefinitely. The P2P based telephony service Skype
benefits from this effect and its growth is limited primarily by market saturation
Network effects give rise to the potential outcome of market tipping, defined as "the tendency of one system to pull away from its rivals in popularity once it has gained an initial edge". Tipping results in a market in which only one good or service dominates and competition is stifled. This is because network effects tend to incentivise users to coordinate their adoption of a single product. Therefore, tipping can result in a natural form of market concentration in markets that display network effects. However, the presence of network effects does not necessarily imply that a market will tip; the following additional conditions must be met:
# The utility derived by users from network effects must exceed the utility they derive from differentiation
# Users must have high costs of multihoming
(i.e. adopting more than one competing networks)
# Users must have high switching costs
If any of these three conditions are not satisfied, the market may fail to tip and multiple products with significant market shares may coexist.
One such example is the U.S. instant messaging market, which remained an oligopoly despite significant network effects. This can be attributed to the low multi-homing and switching costs faced by users.
Market tipping does not imply permanent success in a given market. Competition can be reintroduced into the market due to shocks such as the development of new technologies. Additionally, if the price is raised above customers' willingness to pay, this may reverse market tipping.
Multiple equilibria and expectations
Networks effects often result in multiple potential market equilibrium outcomes. The key determinant in which equilibrium will manifest are the expectations of the market participants, which are self-fulfilling.
Because users are incentivised to coordinate their adoption, user will tend to adopt the product that they expect to draw the largest number of users. These expectations may be shaped by path dependence, such as a perceived first-mover advantage
, which can result in lock-in
. The most commonly cited example of path dependence is the QWERTY
keyboard, which owes its ubiquity to its establishment of an early lead in the keyboard layout industry and high switching costs, rather than any inherent advantage over competitors. Other key influences of adoption expectations can be reputational (e.g. a firm that has previously produced high quality products may be favoured over a new firm).
Markets with network effects may result in inefficient equilibrium outcomes. With simultaneous adoption, users may fail to coordinate towards a single agreed-upon product, resulting in splintering among different networks, or may coordinate to lock-in to a different product than the one that is best for them.
If some existing technology or company whose benefits are largely based on network effects starts to lose market share against a challenger such as a disruptive technology
or open standards
based competition, the benefits of network effects will reduce for the incumbent, and increase for the challenger. In this model, a tipping point is eventually reached at which the network effects of the challenger dominate those of the former incumbent, and the incumbent is forced into an accelerating decline, whilst the challenger takes over the incumbent's former position.
and Victor Company of Japan
(JVC)'s video home system
(VHS) can both be used for video cassette recorders
(VCR), but the two technologies are not compatible. Therefore, the VCR that is suitable for one type of cassette cannot fit in another. VHS's technology gradually surpassed Betamax in the competition. In the end, Betamax lost its original market share and was replaced by VHS.
Negative network externalities
Negative network externalities, in the mathematical sense, are those that have a negative effect compared to normal (positive) network effects. Just as positive network externalities (network effects) cause positive feedback
and exponential growth
, negative network externalities create negative feedback
and exponential decay
. In nature, negative network externalities are the forces that pull towards equilibrium, are responsible for stability, and represent physical limitations keeping systems bounded.
Besides, Negative network externalities has four characteristics, which are namely, more login retries, longer query times, longer download times and more download attempts. Therefore, congestion occurs when the efficiency of a network decreases as more people use it, and this reduces the value to people already using it. Traffic congestion
that overloads the freeway and network congestion
on connections with limited bandwidth both display negative network externalities.
suggests that adding paths through a network can have a negative effect on performance of the network.
has the effect of making the network bigger and thus increases the external value of the network to consumers. Interoperability achieves this primarily by increasing potential connections and secondarily by attracting new participants to the network. Other benefits of interoperability include reduced uncertainty, reduced lock-in, commoditization
and competition based on price.
Interoperability can be achieved through standardization
or other cooperation. Companies involved in fostering interoperability face a tension between cooperating with their competitors to grow the potential market for products and competing for market share.
Compatibility and incompatibility
Product compatibility is closely related to network externalities in company's competition, which refers to two systems that can be operated together without changing. Compatible products are characterized by better matching with customers, so they can enjoy all the benefits of the network without having to purchase products from the same company. However, not only products of compatibility will intensify competition between companies, this will make users who had purchased products lose their advantages, but also proprietary networks may raise the industry entry standards. Compared to large companies with better reputation or strength, weaker companies or small networks will more inclined to choose compatible products.
Besides, the compatibility of products is conducive to the company's increase in market share. For example, the Windows
system is famous for its operating compatibility, thereby satisfying consumers' diversification of other applications. As the supplier of Windows systems, Microsoft
benefits from indirect network effects, which cause the growing of the company's market share.
Incompatibility is the opposite of compatibility. Because incompatibility of products will aggravate market segmentation
and reduce efficiency, and also harm consumer interests and enhance competition. The result of the competition between incompatible networks depends on the complete sequential of adoption and the early preferences of the adopters. Effective competition determines the market share of companies, which is historically important. Since the installed base can directly bring more network profit and increase the consumers' expectations, which will have a positive impact on the smooth implementation of subsequent network effects.
Open versus closed standards
In communication and information technologies, open standard
s and interfaces are often developed through the participation of multiple companies and are usually perceived to provide mutual benefit. But, in cases in which the relevant communication protocols or interfaces are closed standards, the network effect can give the company controlling those standards monopoly power. The Microsoft
corporation is widely seen by computer professionals as maintaining its monopoly through these means. One observed method Microsoft uses to put the network effect to its advantage is called Embrace, extend and extinguish
is an Israel
i start-up which pioneered instant messaging
(IM) and was bought by America Online
. By giving away their ICQ
product for free
and preventing interoperability between their client software
and other products, they were able to temporarily dominate the market for instant messaging. The IM technology has completed the use from the home to the workplace, because of its faster processing speed and simplified process characteristics. Because of the network effect, new IM users gained much more value by choosing to use the Mirabilis system (and join its large network of users) than they would use a competing system. As was typical for that era, the company never made any attempt to generate profits from its dominant position before selling the company.
s and derivatives exchanges
feature a network effect. Market liquidity
is a major determinant of transaction cost
in the sale or purchase of a security, as a bid–ask spread
exists between the price at which a purchase can be made versus the price at which the sale of the same security can be made. As the number of sellers and buyers in the exchange, who have the symmetric information increases, liquidity increases, and transaction costs decrease. This then attracts a larger number of buyers and sellers to the exchange.
The network advantage of financial exchanges is apparent in the difficulty that startup exchanges have in dislodging a dominant exchange. For example, the Chicago Board of Trade
has retained overwhelming dominance of trading in US Treasury bond
futures despite the startup of Eurex
US trading of identical futures contracts. Similarly, the Chicago Mercantile Exchange
has maintained dominance in trading of Eurobond interest rate futures despite a challenge from Euronext.Liffe
also features network effects. Bitcoin's unique properties make it an attractive asset to users and investors, and as more users join the network, the more secure it gets. When the network and community grows, a network effect can occur, making it more likely that new people will join. Also, Bitcoin tends to become financially more valuable as more people invest in it, which may lead to more investors doing the same.
The widely used computer software
benefits from powerful network effects. The software-purchase characteristic is that it is easily influenced by the opinions of others, so the customer base of the software is the key to realizing a positive network effect. Although customers' motivation for choosing software is related to the product itself, media interaction and word-of-mouth recommendations from purchased customers can still increase the possibility of software being applied to other customers who have not purchased it, thereby resulting in network effects.
In 2007 Apple
released the iPhone
followed by the app store
. Most iPhone apps rely heavily on the existence of strong network effects. This enables the software to grow in popularity very quickly and spread to a large userbase with very limited marketing needed. The Freemium
business model has evolved to take advantage of these network effects by releasing a free version that will not limit the adoption or any users and then charge for premium features as the primary source of revenue. Furthermore, some software companies will launch free trial versions during the trial period to attract buyers and reduce their uncertainty. The duration of free time is related to the network effect. The more positive feedback the company received, the shorter the free trial time will be.
Many web site
s benefit from a network effect. One example is web marketplaces and exchanges. For example, eBay
would not be a particularly useful site if auction
s were not competitive. As the number of users grows on eBay, auctions grow more competitive, pushing up the prices of bids on items. This makes it more worthwhile to sell on eBay and brings more sellers onto eBay, which, in turn, drives prices down again due to increased supply. Increased supply brings even more buyers to eBay. Essentially, as the number of users of eBay grows, prices fall and supply increases, and more and more people find the site to be useful.
Network effects were used as justification in business model
s by some of the dot-com companies
in the late 1990s. These firms operated under the belief that when a new market
comes into being which contains strong network effects, firms should care more about growing their market share
than about becoming profitable
. The justification was that market share would determine which firm could set technical and marketing standards and giving these companies a first-mover advantage
websites are good examples. The more people register onto a social networking website, the more useful the website is to its registrants.
Google uses the network effect in its advertising business with its Google AdSense
service. AdSense places ads on many small sites, such as blog
s, using Google technology to determine which ads are relevant to which blogs. Thus, the service appears to aim to serve as an exchange (or ad network) for matching many advertisers with many small sites. In general, the more blogs AdSense can reach, the more advertisers it will attract, making it the most attractive option for more blogs.
By contrast, the value of a news site is primarily proportional to the quality of the articles, not to the number of other people using the site. Similarly, the first generation of search engine
s experienced little network effect, as the value of the site was based on the value of the search results. This allowed Google
to win users away from Yahoo!
without much trouble, once users believed that Google's search results were superior. Some commentators mistook the value of the Yahoo! brand (which does increase as more people know of it) for a network effect protecting its advertising business.
There are strong network effects in the initial choice of rail gauge
, and in gauge conversion
decisions. Even when placing isolated rails not connected to any other lines, track layers usually choose a standard rail gauge so they can use off-the-shelf rolling stock. Although a few manufacturers make rolling stock that can adjust to different rail gauges, most manufacturers make rolling stock that only works with one of the standard rail gauges.
For credit card
s that are now widely used, large-scale applications on the market are closely related to network effects. Credit card, as one of the currency payment methods in the current economy, which was originated in 1949. Early research on the circulation of credit cards at the retail level found that credit card interest rate
s were not affected by macroeconomic interest rates and remained almost unchanged. Later, credit cards gradually entered the network level due to changes in policy priorities and became a popular trend in payment in the 1980s.
Different levels of credit cards separate benefit from two types of network effects. The application of credit cards related to external network effects, which is because when this has become a payment method, and more people use credit cards. Each additional person uses the same credit card, the value of rest people who use the credit card will increase.
Besides, the credit card system at the network level could be seen as a two-sided market
. On the one hand, the number of cardholders attracts merchants to use credit cards as a payment method. On the other hand, an increasing number of merchants can also attract more new cardholders. In other words, the use of credit cards has increased significantly among merchants which leads to increased value. This can conversely increase the cardholder's credit card value and the number of users. Moreover, credit card services also display a network effect between merchant discounts and credit accessibility. When credit accessibility increases which greater sales can be obtained, merchants are willing to be charged more discounts by credit card issuers.
has become a leader in the electronic payment industry through the network effect of credit cards as its competitive advantage. Till 2016, Visa's credit card market share
has risen from a quarter to as much as half in four years. Visa is benefit from the network effect. Since every additional Visa cardholder is more attractive to merchants, and merchants can also attract more new cardholders through the brand. In other words, the popularity and convenience of Visa in the electronic payment market, lead more people and merchants choose to use Visa, which greatly increases the value of Visa.
Coordination and Lock-In: Competition with Switching Costs and Network Effects
Joseph Farrell and Paul Klemperer.
S. J. Liebowitz, Stephen E. Margolis.
The Economics of Networks