Safety in numbers

Safety in numbers is the hypothesis that, by being part of a large physical group or mass, an individual is less likely to be the victim of a mishap, accident, attack, or other bad event.

Some related theories also argue (and can show statistically)[citation needed] that mass behaviour (by becoming more predictable and "known" to other people) can reduce accident risks, such as in traffic safety – in this case, the safety effect creates an actual reduction of danger, rather than just a redistribution over a larger group.

Hamilton proposed his selfish herd theory in 1971 to explain why animals seek central positions in a group.

Each individual can reduce its own domain of danger by situating itself with neighbours all around, so it moves towards the centre of the group.

[2] Antipredator adaptations include behaviour such as the flocking of birds, herding of sheep[3] and schooling of fish.

[4] Similarly, Adelie penguins wait to jump into the water until a large enough group has assembled, reducing each individual's risk of seal predation.

He found an inverse relationship that was hypothesised to be explained by a concept described as 'behavioural adaptation', whereby drivers who are exposed to greater numbers of cyclists on the road begin to drive more safely around them.

Other combined modelling[8][9] and empirical evidence suggests that while changes in driver behaviour might still be one way that collision risk per cyclist declines with greater numbers,[10] the effect can be easily produced through simple spatial processes (traffic design) akin to the biological herding processes described above.

[26] In America, during the period 1999-2007, the absolute number of cyclists killed or seriously injured decreased by 29% and the amount of cycling in New York city increased by 98%.