Statistics for GP and the AKT. Sept ‘ 11. Aims. Be able to understand statistical terminology, interpret stats in papers and explain them to patients. Pass the AKT. Why should you care?. 10% of questions Much less than 10% of the work Easy marks. Plan – don ’ t despair!.
Mean = median = mode
Mean < median < mode
Mean > median > mode
For bonus points, spot the odd one out!
*Chi squared – can be used to compare quantitative data if look at proportions/percentages
“The p value is equal to the probability of achieving a result at least as extreme as the experimental outcome by chance”
i.e. the chance that there is no real difference is less than 5%
Mean ± 1.96 x SEM
= SD / √n
i.e. standard deviation divided by square root of number of samples
As number of samples increases, SEM decreases.
After 30 minutes of stats, the mean reduction in attention span was 2.3 minutes (0.8 – 3.8).
Relative risk of death after learning about stats was 0.7(0.3 – 1.1)
RRR (RRI) = EER-CER
RRI = relative risk reduction
EER = exposed event rate
CER = control event rate
Watch your R’s!
(2=twice as many, 0.5=half as many)
NNT = 1/ARR = 1/EER-CER
It doesn’t need the total.
sensitivity / 1 – specificity
1 – sensitivity / specificity
Size of box
= study size
Odds ratio of
X axis –
Increased precision of study = reduced variance
Asymmetrical funnel = publication bias (missing data/studies)