As we know that QT interval in ECG is a function of heart rate (HR) and to comment on the pathology associated with altered QT interval, we must neutralise the effect of HR. For this Bazett's formula is broadly accepted, i.e. $QT_c=\dfrac{QT}{\sqrt{RR}}$.
Is it purely based on experimental data? Or, there is some mathematical logic behind it?
Here, $QT_c$ = correcred QT interval; $QT$ = measured in original ECG; $RR$ = RR interval.