Forest plots

Question 1

what is meta analysis

Answer 1

-the research process used to
systematically synthesise or pool the findings of single, independent studies to address a specifc
research question.
-calculates overall absolute effect

Question 2

what does meta analysis improve

Answer 2

Improves the precision and accuracy and it will increase the overall statistical power to detect an
effect.

Question 3

what are forest plots

Answer 3

The final estimates from a
meta-analysis are often
reported graphically in the
form of a ’forest plot’.

Question 4

what does the horizontal line represent

Answer 4

Each horizontal line
represents a single study

Question 5

what does the box mean

Answer 5

Box = standardized effect
size, area / size – weight
of study

Question 6

what does the diamond show

Answer 6

Overall effect size

Question 7

what does it mean if OR or RR is 1

Answer 7

then the effect in the
intervention is the same as the effect in the control group

Question 8

what does it mean If OR or RR is >1

Answer 8

then the effect in the
intervention group is greater than the effect in the control group
* the effect could be good or bad

Question 9

what is Heterogeneity

Answer 9

This is a measure of the differences
between the studies (e.g. methodology, study population
etc) included in the meta-analysis

Question 10

What is publication bias

Answer 10

if studies are biased, pooled results are biased.

Question 11

what are the potential causes of bias

Answer 11

confounding, drop-outs,
non-validated measures, biased analysis interpretation etc