Measures of occupational prestige for each ego at each wave were also available (see appendix on bmj)
Over the course of follow-up, the participants spread out across the United States but continued to participate in the Framingham Heart Study. As a person’s family changed because of birth, death, marriage, or divorce, and as their contacts changed because of residential moves, new places of employment, or new friendships, this information was captured. For any given ego, a particular alter can be in only one mutually exclusive category-that is, spouse, sibling, friend, coworker, or neighbour.
For 39% of the egos, at least one coworker participated in the study
There were 53 228 observed social ties between the 5124 egos and any other alters in any of the Framingham Heart Study cohorts, yielding an average of 10.4 ties to family, friends, and coworkers over the course of follow-up. Additional ties to neighbours were also ascertained, based on information about place of residence, but they are not included in the foregoing count as the number of neighbour ties depends on how “neighbour” is defined (for example, whether we restrict the definition to immediate, next door neighbours, or neighbours residing on the same block within 25 or 100 metres, etc).
Given the compact nature of the Framingham social network in the period 1971-2007, many of the nominated contacts were also participants in one or another Framingham Heart Study cohort32 34 so we have detailed survey and physical examination information about both the ego and the alter. For example, 83% of egos’ spouses were directly and repeatedly observed and 87% of egos with siblings had at least one sibling who also participated in the Framingham Heart Study. For 10% of the egos, an immediate neighbour was also in the Framingham Heart Study.
Importantly, 45% of the 5124 egos were connected via friendship to another person in the study; there were 3604 unique observed friendships for an average of 0.7 friendship ties per ego. There was substantial variation from person to person, ranging from several people with no friends to one person who was nominated as a friend by eight different Framingham Heart Study participants. Because friendship identifications are directional, we can study three different types. An “ego perceived friend” means the ego nominates an alter as a friend, but the nomination is not reciprocated. In this case the ego thinks of the alter as a friend, but the alter might not think of the ego as a friend. An “alter perceived friend” means that an alter nominates the ego as a friend but not vice versa. Here, the ego might not feel any closer to the alter than he or she would to a stranger. Finally, a “mutual friend” is one in which the nomination is reciprocal.
We can be reasonably confident that when someone names someone else as a friend, then the namer feels close to or esteems the namee. We should not, however, read too much into a particular failed nomination. The namer might have several equally good friends and might simply have omitted one or more 
of them. On the other hand, we would expect on average that people feel closer to the people they name than the people they do not name. By the same reasoning we expect on average that, in one way nominations, the namer feels closer to the namee than vice versa. We therefore hypothesised that the influence a friend has on an ego would be affected by the type of friendship, with the strongest effects occurring between mutual friends, followed by ego perceived friendships, followed by alter perceived friendships.
At inception, 53% of the egos were women; the egos’ mean age was 38 years (range 21-70); and their mean education was 1.6 years of college (range 0-?17 years of education).