Reading focus
Syllabus: How Do Eating Disorders Develop and Persist?
Distinguish exact and relaxed versions of the predicted sequence, and examine how thresholds determine the apparent order.
Why you’re reading it. Move from maintenance to a test of developmental onset while keeping prediction separate from causation.
A question to consider. How would the model’s apparent support change if “following the sequence” required every risk factor to occur in the specified order?
Why this reading
A developmental explanation predicts an order, not merely a set of correlated risk factors. Stice and Van Ryzin examine when proposed risks emerge in relation to eating-disorder onset. Their study exposes the choices involved in translating a causal diagram into a longitudinal test with thresholds and estimated transition times.
Before you read
Prospective research measures people before a later outcome occurs. A risk factor predicts an outcome; prediction alone does not identify a cause. A threshold converts a continuously varying score into a classification. Self-reported dietary restraint and objectively measured intake are different constructs.
Read for
- Follow how risk thresholds and estimated ages of emergence were constructed from annual assessments.
- Distinguish the exact predicted sequence from the relaxed version allowing a missing or out-of-order risk factor.
- Identify which disorders were included in the outcome and which explanations of the ordering remain possible.
Consider afterwards
- How might a different threshold change whether a person appears to follow the proposed developmental sequence?
- Design a stronger test of one causal link that does not treat temporal precedence as sufficient evidence.
Editorial context
The study followed 496 adolescent girls over eight years. Its incident cases concern bulimia nervosa, binge-eating disorder and purging disorder, including subthreshold presentations—not all eating disorders. Less than half of incident cases followed the exact sequence; a larger proportion fitted relaxed criteria. Annual measurements and estimated crossing times do not directly observe month-by-month transitions. The threshold procedure also needs validation beyond the cohort in which it was developed.