Level of evidence | Designs | Data sources | Outputs |
Signal detection/Hypothesis generation | Observed vs expected analyses | Spontaneous reports, observational databases | Binary signal/non-signal based on predefined thresholds and observed values |
Scan statistics | Observational databases | Binary signal/non-signal based on event clustering | |
Self-controlled case series | Spontaneous reports, observational databases | Incidence rate ratio | |
Time-to-onset analyses | Spontaneous reports | Binary signal/non-signal based on predefined thresholds and p values | |
Sequential methods | Observational databases | Binary risk/non-risk based on predefined stopping rule | |
Hypothesis strengthening | Ecological methods including interrupted time series (ITS) | Observational databases, surveillance data | Incidence rate ratio, p values for slope or level change (in ITS) |
Hypothesis testing | Cohort-based studies | Prospective cohorts, observational databases | Absolute risk, hazard and survival functions |
Case-referent studies | Observational databases | Odds ratio, Hazard ratio | |
Self-controlled methods | Observational databases | Incidence rate ratio |
*Observational databases include population-based health database such as administrative billing and electronic health record databases.