Hi everyone!
Recently, I've been working on a systematic review and meta-analysis, and I needed to calculate EDSS (a disease severity score) for multiple sclerosis patients.
Imagine that a study has divided patients into subgroups A and B.
The score of all patients (N=174) is 2.43±1.94, and the subgroup A (N=76) score is 2.50±1.99.
Is there any calculator or code that can provide me with the mean and SD of subgroup B?
I already know calculators such as https://www.statstodo.com/CombineMeansSDs.php can combine subgroups and provide the whole mean and SD.
I appreciate your answers! :)
You could probably try to find the answer using the link between the whole group mean and SD vs other subgroups means and SD (as in the Cochrane textbook: https://handbook-5-1.cochrane.org/chapter_7/table_7_7_a_formulae_for_combining_groups.htm )
The mean of subgroup A can be calculated from the following formula:
μA = [(μ * N) - (μB * nB)] / nA
Where μA is the mean of Subgroup A
μB is the mean of Subgroup B
nB is no.of.observations in group B
nA is no.of.observations in group A
N is the total no.of.observations
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