Combining data from various trials to obtain weighted mean and SD

#1
Hi folks.

I need help with some data. It is very basic but I have been out os school for longer than I wish to divulge.

I wish to obtain data from a a systematic review. The paper has presented a bar chart but I can't interpret the numbers from the scale and the SD. The appendix has the studies they used in the RCTs or whatever type of study they used. They give the number of patients in the study, the mean bone gain in mm and SD.

I need to know how to combine several of these studies to obtain the weighted mean and SD so I can place figures on the bar chart.

Many thanks for your help in advance.

J
 

hlsmith

Less is more. Stay pure. Stay poor.
#2
Well if you are trying to recreate their bar chart and numbers, you will need to know the exact analyses they performed. So I am assuming they may have conducted a meta-analysis - which may have used fixed or random effects for example. If you can figure all of this out, you can likely get close to recreating their numbers - but a lot of details may be needed, down to the software they used.

Can you provide a link to the systematic review you are referencing and which figure?
 
#3
That is incredibly helpful of you.
The article is "Clinical efficacy of grafting materials in alveolar ridge augmentation: A systematic review*" Figure 7 is what I am interested in. Unfortunately I cannot find a free copy of it online and it is too large to attach here.
What would you suggest?
Many thanks