The specific queries are;
1. The baseline value in a study is 47.9±13.6 (mean ±SD) and the percentage reduction following intervention is 69.1±14.9 (mean ±SD). How to get the final post interventional SD value by calculating the percentage reduction from baseline SD?
2. The baseline value is 1702.7±876 (mean ± SD) and the average decrease after intervention is 38.27% (95% CI for percent change is -58.59 to -17.94; p=0.0047). How to calculate the final SD value post intervention?
Can anybody please guide us whether it is possible to calculate SD using any formula, with the above available details?
No, it is not possible without knowing (or assuming) the actual distribution of the values. The distribution for the baseline values will be different to the distribution of the percent change values. If these distributions were known or reasonable assumptions about these distributions exist then one can use a simulation technique (parametric bootstrap) to generate post intervention values and calculate their SD.
Thank you very much for the answer. Unfortunately, I could not get the actual post intervention value from the original author of a study for meta-analysis and hence I posted this query.
My preintervention values in group a and group b are 83.78±38.16 and 216 ±121.73 and post-intervention values are 36.20±29.75 and 35.40±14.71.In this scenario,how do we calculate the percentage reduction in values in both group A and Group B ? Please Help
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