[MUSIC] Now, another important thing to realize is that not everybody in a reference network is equally important. Sometimes, religious leaders are crucial in one's reference network. Sometimes one's family, one's relatives. Think of the Middle Eastern that look at their families and friend, continents apart, to decide what to do with a straying daughter. Sometimes are community leaders, sometimes are people you work with. So, it depends very much on the situation at hand. Let's hear some examples. >> Basically, most people care about the opinion of their neighbors. Those who are close to them. They also care about the opinion of their leaders, their community leaders, religious leaders and the opinion leaders within the community. Those who, if they found out that they were practicing open defecation was certainly not approve of it. It matters to them a lot that such people will find out exactly that they're involved in practicing open defecation, so they care. >> I think it's different in every community. In cases like in Zambia where the traditional leaders have a lot of influence on how people behave. In places, it's the religious leader. In other places I've worked, outsiders even play a role in motivating others to change their behavior. >> It would be as much pressure if somebody outside, say the health office, comes and tells them about the dangers of this in terms of disease and the risk. So this is a guy coming from somewhere and telling us what to do. Who is he? But it's another matter when their chief, when their neighbor. When the children going to school, they learn that this is a very, very dangerous thing. And they are like sibling, they are like children, they say, look, you people. This was happening within your own household, they'll come back and put pressure there for me. [INAUDIBLE] as well. So, that happens. So, the pressure comes from so many different points that actually people change. >> Reference networks have a network factor, and what do I mean by that? I give you some example. Look at this particular network. This network has a center, i.e., there is a person there who has a lot of connection with other people that do not connect to each other. So, they connect only to this person. It may be a case where a religious leader dictates certain behavior and people just look at the religious leader, they don't look at each other. The religious leader is at the center of their network. And so in these cases, you would want to approach the religious leader if you aim, for example, to obtain a change in behavior. Another situation, which is far more common, is one in which you have a set of dispersed networks. Dispersed, but connected. So you can see that in each network, there is a central person who has a quite a few connections with other people. And usually, this central person has a connection with other networks. In this example, there are one, two, three, four small networks that all connect to the central network. And then there is this interesting case in which, like in the centralized network, all the people had a far more similar number of connection, rather than one person or a small set of people dominating the network. Depending on the particular network being represented, this might mean that influence is much more dispersed among the people. Or that information could spread through many different channels rather than having to flow through a small set of key individuals.