Table 4.

Preprocessing methods.

Preprocessing method	Method		References
Filtering	Butterworth, median filtering, moving average, FIR		Godfrey et al., 2011; van Hees et al., 2013; Skotte et al., 2014; el Achkar et al., 2016; Spinsante et al., 2016, Makikawa and Murakami, 1996; Adaskevicius, 2014; Bayat et al., 2014; Garcia-Ceja and Brena, 2016,
Signal segmentation	Windowing technique	Sliding window	Bonomi et al., 2009; Gyllensten and Bonomi, 2011; Reiss and Stricker, 2011; Bisio et al., 2012; Nguyen et al., 2013; van Hees et al., 2013; Barshan and Yuksek, 2014; Bayat et al., 2014; Shoaib et al., 2014; Skotte et al., 2014; Garcia-Ceja and Brena, 2016
		Activity-based window	el Achkar et al., 2016; Spinsante et al., 2016
Feature extraction	See details in Table 5.
Feature selection	PCA		Gyllensten and Bonomi, 2011; van Hees et al., 2013; Barshan and Yuksek, 2014
	Clustering		Reiss and Stricker, 2011; Bayat et al., 2014