Statistics Flashcards
WHAT IS BIAS
DESCRIBE POTENTIAL SOURCES AND HOW THESE CAN BE MINIMISED
Bias = systemic error that distorts study findings
Caused by flaws in study design, collection, analysis
Can occur at any stage from literature search to publication
Selection Bias - selection of patients in same group that is not random - AVOID BY randomising selection
Detection Bias - observer makes subjective decisions about the outcome. AVOID BY blinding the observer and making outcomes Objective rather than subjective
Recall Bias - Patients know whether they were allocated to treatment or control group and behave differently. AVOID BY blinding participants
Publication Bias - influence of study results on publication eg less likely to publish negative findings over positive findings. leads to publish of mostly positive (or negative) data
Overall influences Meta-analysis data
Also authors may only search for english, free-access or narrow search keywords.
AVOID BY - contacting authors and obtaining all unpublished trial data, searching in all languages, search across multiple speciality databases.
Response Bias - patients enrol themselves in the trial, results in non representative sample. AVOID BY randomly sampling population
WHAT IS EVIDENCE BASED MEDICINE
DESCRIBE FEATURES OF SYSTEMATIC REVIEW, indicating how it may influence your practice of anaesthesia
EBM is the conscientious explicit and judicious use of current based evidence in making decisions about care of individual patients
Systematic review features: Identify clinical question define inclusion and exclusion criteria extensive international literature research - select and appraise all relevant research Assess quality of included studies extract data analyse data presentation and interpretation of results
Large systematic reviews are designed to collate all empiric evidence and analyse it with a view to minimise bias and therefore provide more reliable results.
A large systematic review may influence practice if a significant finding is made it may change national/internation guidelines changing clinical practice.
allows evidence for judicious use of knowledge in a clinical situation for an individual patient
