“Schmittmann et al. (2013). Deconstructing the construct: A network perspective on psychological phenomena.” - Article summary

In the reflective model, the attribute is seen as the common cause of observed scores (e.g. depression causes people feeling sad). In the formative model, observed scores define or determine the attribute (e.g. depression occurs when people feel sad a lot).

Reflective models are presented as measurement models. A latent variable is introduced to account for the covariance between other variables. In the reflective model, variables are regarded as exchangeable save for measurement parameters (e.g. reliability) and correlations between the variables are spurious in the reflective model. The correlation only exists because variables are related and might be the same thing.

Formative models differ from reflective models because the variables are not exchangeable. This is because variables are hypothesised to capture different aspects of the same construct. There is also no assumption about whether the variables should correlate.

There are three problems with the conceptualization of reflective and formative models:

1. Time
   In reflective and formative models, time is not explicitly represented. The precedence criteria for causal relationships is not taken into account.
2. Inability to articulate processes
   The processes of causal mechanisms cannot be described and tested using these models.
3. Relations between observables
   Causal relationships between observable variables are neglected in these models as the models do not account for these relationships, although it is likely that there is a causal relationship between at least some observable variables.

The network model states that observable variables of latent variables should be seen as autonomous causal entities in a network of dynamical systems.