Table 1 Summary of statistical methods based on the types of variables

Symmetric continuous variable

\( \overline{X}\pm s \)

\( \frac{{\overline{X}}_2-{\overline{X}}_0}{\sqrt{\left({s}_2^2+{s}_0^2\right)/2}} \)

Independent samples t-test

Paired samples t-test

Non-symmetric continuous variable

m [q₁ − q₃]

The standardized difference defined above for lnX

Wilcoxon’s rank sum test

Wilcoxon’s signed rank test

Count variable

c

Standardized difference for symmetric continuous variable

Independent samples t-test

Paired samples t-test

Binary variable

\( f\ \left(\hat{p}\%\right) \)

\( \frac{\hat{p_2}-\hat{p_0}}{\sqrt{\left(\hat{p_2}\left(1-\hat{p_2}\right)+\hat{p_0}\left(1-\hat{p_0}\right)\right)/2}} \)

Fisher’s exact test

McNemar’s test