Andrew@Reliabilityoxford.co.uk
A brief reminder that the key outcome measures from epidemiology are often expressed as risk or odds ratios.
A ratio of 1.0 indicates that the exposure effect relationship being tested shows neither an increased nor a decreased risk. That is, there was no detectable association between hypothetical cause and effect.
A ratio of less than 1.0 (but more than 0.0) indicates that the exposure might be protective against the outcome. A ratio of more than 1.0 indicates increased risk.
Similarly, a standardised mortality ratio (SMR) of 100 indicates no detected risk.
In terms of probabilities, a risk ratio of more than 2.0 (or more than 200 for SMR) indicates that there is a probability of an association between exposure and outcome of more than 50%. This would seem to satisfy the test of the balance of probabilities.