Bias + Funnel Plot Flashcards
(14 cards)
What is bias?
Described the situation in a trial where one outcome is systematically favoured
What is selection bias?
Error in assigned individuals to groups > differences which may influence the outcome
What is sampling bias
Subtype of selection bias where the subjects are not representative of the population
What is recall bias?
Difference in the accuracy of recollections retrieved by study participants
What is publication bias?
Failure to publish results from valid studies, as they showed negative or uninteresting results
What is information bias
Due to inaccuracies in measurements or classifications of variables
What is observer bias?
Researcher’s expectations influence recording/interpretation of study results
What is responder bias?
When participants give repsonses that they believe are expected or desirable, rather than their true noughts
What is confounding?
Refers to a variable which correlates with other variables within a study > inaccurate results
How to reduce confounding?
Randomisation
Intention to treat analysis
How can publication bias be detected?
Funnel plot
Galbraith plot
Outline funnel plot
- graph used to check for for publication bias in systematic reviews + meta-analysis
- form of scatter graph that offers an easy visual way of ensure even weighing
- symmetrical, inverted funnel shape indicates that publication bias is unlikely
- asymmetrical funnel indicates publication bias or small study effects
Interpretation of funnel plots
- symmetrical inverted funnel shape indicates that publication bias is unlikely
- asymmetrical funnel shape indicates publication bias or small study effects
What is small study effect?
When smaller studies show different treatment effects than larger studies
