It’s who you know

We’ve all heard the expression “it’s not what you know, it’s who you know.” Well, academic research suggests that this theory may be a significant factor in the adoption of innovation. A 1950s study on the diffusion of a new antibiotic highlights the point.

In 1954, Charles Pfizer and Company gave a $40,000 grant to three Columbia University sociologists to study the uptake of medicines. Pfizer originally wanted to understand the influence of advertisements in medical journals on the adoption of its products. However, the research quickly transformed into a significant study on the role interpersonal communication networks play in the uptake of new medicines. 70 years later, it’s still considered one of the most important diffusion studies of all.

The focus of the study was the diffusion of tetracycline, a new antibiotic launched by Pfizer in 1953. Tetracycline’s primary selling point was that it had fewer side-effects than existing antibiotics. Research began with a small pilot in New England, before extending to four cities in Illinois. Researchers interviewed 228 doctors – 64% of all practicing doctors in the four cities, including 85% of doctors from relevant specialties. By the time the research began, 87% of doctors in the study had prescribed tetracycline at least once. The study sought to determine how quickly they’d adopted it and what had persuaded them.

Prescription records from drugstores were used to provide objective evidence of each doctor’s adoption time. Alongside this, doctors were asked three sociometric questions: who did they turn to for advice and information? With whom did they discuss cases during a normal week? And who, amongst peers, were the friends they saw socially. For each question, respondents were asked to name three doctors. The aim was to establish how each doctor was connected in the medical community, and whether this presented any clues to adoption.

The findings underlined the role of interpersonal networks in diffusion. ‘Opinion leaders’ – doctors designated as ‘social friends’ by three or more peers – had adopted tetracycline by the eighth month of the 17-month diffusion period. This early adoption by opinion leaders stimulated a rapid increase in uptake among their followers, producing an S-shaped diffusion curve. The study showed that opinion leaders’ subjective evaluations of tetracycline, based on their personal experiences, were key in persuading peers to adopt it.

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“Ultimately, a colleague’s recommendation had a more significant persuasive impact than scientific evaluations alone.”

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The study also revealed the impact of a doctor’s network position. Isolated doctors – those not connected to others – took longer to adopt tetracycline than those who were connected. Research into why doctors chose specific peers as ‘social friends’ showed that religion, age, hometown and alma mater all played a part. However, personal affiliations – like working at the same hospital or being part of the same office partnership – were primary determinants.

The results of the study are compelling. Although doctors had been given ample information about tetracycline – through clinical data and rep detailing – that wasn’t enough to convince them to adopt. Personal endorsements from peers, based on firsthand experience, were critical. Ultimately, a colleague’s recommendation had a more significant persuasive impact than scientific evaluations alone.

The Columbia University study undelines the vital role of interpersonal networks in the diffusion of innovation. Peer influence through social interactions is a powerful factor in persuasion.