Table 2.

Nine time domain statistical parameters.

Domain	Indexes	Formula
Time	Average Value Tavg	$T_{avg}={\displaystyle \sum _{j=1}^n{x}_j}/n$
	Root mean square Trms	$T_{rms}=\sqrt{{\displaystyle \sum _{j=1}^n{x}_j^2}/n}$
	Standard Deviation Tsd	$T_{sd}=\frac{1}{n-1}\sqrt{{\displaystyle \sum _{j=1}^n{(x_j-T_{avg})}^2}}$
	Crest Factor Tcf	$T_{cf}=\max \left\{\left|x_j\right|\right\}/T_{rms}$
	Shape factor Tsf	$T_{sf}=T_{rms}/T_{avg}$
	Waveform Twf	$T_{wf}=n\cdot T_{rms}/({\displaystyle \sum _{j=1}^n\left|x_j\right|})$
	Kurtosis Factor Tku	$T_{ku}=({\displaystyle \sum _{j=1}^n{(x_j-T_{avg})}^4})/(n\cdot T_{sd}^4)-3$
	Skewness Factor Tsk	$T_{sk}=({\displaystyle \sum _{j=1}^n{(x_j-T_{avg})}^3})/(n\cdot T_{sd}^3)$
	Margin factor Tmf	$T_{sk}=n^2\cdot \max \left\{\left|x_j\right|\right\}/{({\displaystyle \sum _{j=1}^n\sqrt{\left|x_j\right|}})}^2$