Praedicat’s general causation score ranges from -1 to 1. A score of -1 implies general rejection of the hypothesis by scientists while a score of +1 implies general acceptance of the hypothesis by scientists. A score of zero indicates that the evidence overall is equivocal.
Calculating general causation
The general causation risk model is the primary means by which Praedicat contextualizes the scientific literature regarding the hypothesis that a Litagion agent causes a type of bodily injury. The general causation risk model is a weight-of-evidence model that conceptually mimics how an expert panel of human researchers would evaluate the hypothesis in light of Hill’s criteria of establishing causation.
To calculate the general causation score, Praedicat extracts metadata from individual scientific papers and then combines the data to create literature metadata. At the literature level, the individual studies are aggregated and weighted to reflect the relative weightings that scientists would be expected to place on the studies. For instance, studies that are published in the most well-respected and cited journals are viewed as more authoritative and of higher quality. Praedicat uses an authoritative and external ranking of journals to assign a “quality weight”. The outcome of the studies, effect size and study type metadata combine with “quality weight” data to give an article its relative weight in the general causation score. Each study can be classified into a category indicating the study’s ability to show a causal link between Litagion agent and harm.
When Praedicat calculates a general causation score on a full literature, we include all factors to get each paper’s individual weight and then sum them to get the overall weight of the literature. While positive results are added, negative results are subtracted. If the literature is based entirely on animal evidence, it further restricts the ranges of scores to (-0.5, 0.5), embodying our belief that human evidence is required to sustain a claim in court. Once human evidence exists in the literature, this module changes the output range of the GC score: a completely human literature is restricted to (-0.75, 0.75) and a good mixture of both animal and human literature allows the full (-1.0, 1.0) range to be used. This embodies our observation that having corroborating evidence from both animal and human studies raises the likelihood of sustaining a bodily injury claim in court.
In summary, Praedicat’s general causation scoring algorithm weighs the relative importance of the articles comprising a Litagion agent-bodily injury hypothesis using journal quality weightings, study types and effect size while also taking into account the relative presence of human and animal studies in the literature. The model takes into account how expert panels read and review science while also paying homage to the Hill criteria that establish epidemiological causation.