rognosis research investigates prognosis of individual patients. Factors that influence prognosis of a therapy are called prognostic factors. Homeopathic symptoms are prognostic factors: the symptom ‘Desire for salt’ indicates that some homeopathic medicines, like Natrium muriaticum, are more likely to work.

According to Bayes’ theorem the chance that a medicine works if a specific symptom is present increases if the Likelihood Ratio (LR) of that symptom for the medicine is above one.

LR = (prevalence in target population) / (prevalence in remainder of the population). The LR can be calculated from a research population of 4094 subjects as follows:

In every new patient in this population the symptom ‘Grinding teeth during sleep’ was checked; there were 219 patients with this symptom. At the end of the assessment there were 21 patients responding well to Belladonna, 6 of them had ‘grinding teeth during sleep’. So the prevalence of this symptom in the Belldonna population is 6/21=28.6%. Likewise, we can calculate the prevalence of this symptom in the remainder of the population: 5.2%. The resulting LR = 28.6/5.2= 5.5.

Higher LR means that the symptom is a stronger indication for the corresponding medicine. Repertory rubrics based on LR values are more valid in scientific respect. After prognosis research our repertorisations will be more accurate but look the same, see below.