What Is Social Network Theory?

Visual representation of the Social Network Theory

Social Network Theory is the study of how people, organizations or groups interact with others inside their network. Understanding the theory is easier when you examine the individual pieces starting with the largest element, which is networks, and working down to the smallest element, which is the actors.

Examining Networks

In some ways, networks can be thought of as neighborhoods, since networks are comprised of the actors and the relationships between those actors. These actors, referred to as nodes, can be individuals, organizations or companies. Regardless of what they are, they are always the smallest single unit inside a network. If you view the United Nations as a social network, the United States would be a node or actor inside the network.

The three types of social networks that social scientists explore are ego-centric networks, socio-centric networks, and open-system networks.

  • Ego-centric networks are connected with a single node or individual. For example, you, the node, connected to all your close friends.
  • Socio-centric networks are closed networks by default. Two commonly-used examples of this type of network are children in a classroom or workers inside an organization.
  • In open-system networks, the boundary lines are not clearly defined. A few examples in this type of network are America's elite class, connections between corporations, or the chain of influencers of a particular decision. Due to the lack of clearly-defined boundaries, this type of network is considered the most difficult to study.

Studying Relationships

If networks were just a list of your close friends or the people you work with, there would be nothing to study. What social scientists are concerned with are the interactions between each of the members of the network. These connections, called relationships or ties, are at the heart of what social scientists seek to study and understand. Why do the individuals interact, how do they interact and what is the level of closeness -- usually referred to as connectedness -- between group members?

Although, there are many types of relationships, including reciprocal, directional and others, each of the types can be reduced to either a strong tie or a weak tie.

Weak Versus Strong Ties

Strong ties are close enough to you that you probably have the phone numbers of these people, whereas weak ties would be surprised if you called one of them. However, research shows that the weak ties in your network are, in some ways, more valuable. One study conducted by John S. Granovetter of John Hopkins University determined individuals who sought employment most often received more quality job leads from weak links than from strong ones.

Nodes or Actors

Nodes can most easily be defined as the individual players -- or actors -- inside the network. Inside this part, which is the smallest piece of the social network puzzle, is where scientists, marketers and even politicians, try to analyze the ties a node has with the other members of the network.

As an example of a social network, consider the members of a church. Despite the fact all of them are connected by the overall network, not all the individuals are connected with the same degree of closeness. It's these varying degrees of closeness, or connectedness, that determine the value of that node to the network.

An actor's location inside the social network can be an indicator of the strength of the ties associated with him. A person near the center of the network often has more ties -- or links -- between himself and the other actors, as opposed to someone on the outer fringes of a network. A person on the outer edge of the network could be connected to the network by only one link.

Six Degrees of Separation

One of the most fascinating aspects of Social Network Theory is the six degrees of separation concept. This concept was the outcome of a late 1960s social experiment called The Small World Problem, conducted by Stanley Milgram, in which 100 letters were sent to randomly chosen individuals with a set of instructions to get the letter to a specific individual who lived in Sharon, Massachusetts. However, a couple of stipulations determined how the letter could reach the Sharon, MA target.

  • First, recipients of the letter could only send the letter to someone they knew firsthand, but that person should be someone they thought may know someone who knew the target.
  • Second, if the recipient knew the target, they were to directly mail the letter to the target.

In the course of the experiment, Milgram determined that there were, on average, six steps between the initial person who received the letter and the Sharon, MA target. The theory also led to the creation of a common trivia game, 6 Degrees of Kevin Bacon.

Weakness of Milgram's Claim

One criticism of Milgram's work is the lack of data to support his theory, since many of the letters never reached their intended target. In 2003, a group of scientists at Columbia University in New York set out to replicate the experiment, using email instead of traditional paper and U.S. mail. Just like in the original study, a significant percentage of the emails were abandoned, which broke the chain. The scientists stated these chains were broken due to the "lack of incentive by individuals to reach a target." However, even with the high number of broken chains, emails that did reach the intended target did so in five to seven steps, which mirrored Milgram's original experiment.

Strengths and Weaknesses of the Theory

Due to the complexity of any social network, using the theory to understand actors and the relationships between them is crucial to the work of social scientists, theorists, politicians, and even marketers. These researchers often try to glean a better understanding of the inner workings of a network so they can further their cause or simply sell a product. The theory, though, does have some inherent strengths and weaknesses.


  • The theory offers an explanation for how random people are connected.
  • It's useful in the study of large groups and understanding how their members relate to others in the group
  • It provides insight into viral phenomena, such as viral content, the spread of diseases like ebola, etc.


  • It's difficult to scientifically replicate.
  • Interpreting relationships/ties can be subjective.

Theory In Practice: Social Media

The theory is used to understand everything from high employee turnover to the intricate webs associated with terrorist networks. In many ways, its the math behind social network theory that explains how a piece of social media content goes viral in relatively few steps. This math, power functions, shows how a small change in one area can have a huge impact in the overall network. When a change is initiated at the node level, the change moves first from the node, along its ties to the various connected relationships, before being pushed out to additional nodes and their relationships, creating a change throughout the entire social network.

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What Is Social Network Theory?