Discuss how longitudinal research in general, and panel research in particular, is arguably the best suited for illuminating cause and effect relationships, using this article as a template.
In particular, while the results of the study examining donated brains of deceased NFL players initially appears to be damning to the NFL in particular, and tackle football in general, I ask students to tailor their discussion toward addressing the need for time-series, longitudinal research, on this important matter. In other words,
o (a) does the current research on CTE, meet all of the criteria for nomothetic causality; and
o (b) if not, how might longitudinal research help meet these criteria?
In essence, based on what you have learned this term, apply the three criteria of nomothetic causality to this study, and discuss whether or not all criteria are met with this research (are there any potential selection effects in operation here?).
Will this longitudinal research change your views on participating in contact sports? Why or why not?
Time Order
Assessment: CHALLENGED. While we know the cause (playing football) preceded the effect (death/CTE diagnosis), the existing research cannot pinpoint when the critical causal factor (repeated subconcussive hits) initiated the pathology or if the damage was cumulative. It establishes the sequence of events but not the sequence of pathogenesis.
3. Nonspuriousness
Assessment: NOT MET. This is the largest weakness. The samples used in these studies are heavily affected by a selection effect (or selection bias).
Selection Effect: The vast majority of brains studied were donated because the individuals exhibited symptoms of cognitive, behavioral, or mood decline (dementia, aggression) before death. This self-selection means the sample is not representative of all deceased football players, only those who were symptomatic.
The Problem: The current data cannot rule out a spurious relationship where a third variable—such as a genetic predisposition, the presence of untreated pre-existing mental health issues, or lifestyle factors—influenced both the decision to play contact sports and the likelihood of developing severe cognitive symptoms leading to brain donation.
Sample Answer
Longitudinal research, particularly panel research, is superior for establishing cause-and-effect relationships because it directly addresses the critical requirement of time order in nomothetic causality, which cross-sectional or retrospective studies cannot definitively establish.
The current research on Chronic Traumatic Encephalopathy (CTE) in deceased NFL players, while alarming, relies heavily on post-mortem, retrospective analysis of donated brains. This methodology struggles to fully meet the criteria for nomothetic causality.
Nomothetic Causality and the CTE Studies
Nomothetic causality requires three criteria to be met: Covariation, Time Order, and Nonspuriousness.
1. Covariation (Correlation)
Assessment: YES. The current research demonstrates a strong statistical association (covariation) between the exposure (years and intensity of tackle football) and the effect (the presence and severity of CTE pathology).