Skip to main content

Table 1 Formula for combining groups of continuous data

From: Nefopam for the prevention of perioperative shivering: a meta-analysis of randomized controlled trials

  Group 1 Group 2 Combined group
Sample size N1 N2 N1 + N2
Mean M1 M2 \( \frac{N_1{M}_1+{N}_2{M}_2}{N_1+{N}_2} \)
Standard Deviation SD1 SD2 \( \sqrt{\frac{\left({N}_1-1\right)S{D_1}^2+\left({N}_2-1\right)S{D_2}^2+\frac{N_1{N}_2}{N_1+{N}_2}\left({M_1}^2+{M_2}^2-2{M}_1{M}_2\right)}{N_1+{N}_2-1}} \)