Neighbours and work colleagues can all potentially have an influence on our behaviour. For instance, poor health behaviours amongst neighbours and colleagues may normalise and reinforce our own poor health behaviours. This is one example of a peer effect. Imitative behaviour can cause small initial changes in individual behaviour to spread amongst their social networks and result in a ’social multiplier’ effect. Understanding the size and mechanisms behind the ’social multiplier’ effect allows for more effective health interventions. It also helps us understand why persistent health inequalities exist across different neighbourhoods and social groups.
The NILS and SLS study are longitudinal studies with 28% and 5% census samples respectively. The high sampling rate means that a proportion of both LS samples will be neighbours living in the same postcode and employees in the same workplace. This presents an opportunity to test the existence of peer effects from neighbours, colleagues and classmates. Both LS have great potential for studying peer effects.
Using instrumental variables in parallel with an analysis of close neighbours, we will test the causal effect of women’s fertility on the fertility of their neighbours and work colleagues. The unique nature of Northern Ireland also allows us to test the degree to which peer interactions are mediated by religion in NILS compared to the SLS.
In addition, we also wish to map the network characteristics of NILS members as a proof of concept for future projects that may wish to use the data for other health based research questions (e.g. modelling the spread infectious diseases).
This NILS project is associated with a corresponding SLS project (2020_02) to look at peer effects in fertility in Scotland.