Forest Plot + CI + SD Flashcards
(12 cards)
What is a forest plot used for?
Used as a visual tool for meta analysis
What does a square represent in a forest plot?
Odds ratio
What do the lines represent on a forest plot?
95% confidence interval
In a forest plot, what does the size of the square represent?
The bigger the square, the more weight the study held in a meta analysis
What does a diamond represent on a forest plot?
Pooled estimate odds ratio
The odds ratio + confidence intervals of all studies in the meta-analysis
What does a confidence interval at 95% confidence level mean?
The confidence interval should contain the true effect of intervention 95% of the time
What is the confidence interval?
A range of values within which the true effect of intervention is likely to lie
What does it mean if the confidence interval:
- spans 1
- >1
- <1
- spans 1: not statistically significant
- >1: favours new drug
- <1: favours old drug
Properties of normal distribution:
What % of values lie within:
- 1 SD of the mean
- 2 SD of the mean
- 3 SD of the mean
- 1 SD of the mean: 69%
- 2 SD of the mean: 95%
- 3 SD of the mean: 99.7%
What is standard deviation?
A measure of how much dispersion exists from the mean
What is variance?
A measure of the spread of scores away from the mean
Square of standard deviation
What does it mean if the range of the mean absolute difference crosses O?
Not statistically significant
