Feature Selection for Longitudinal Data by Using Sign Averages to Summarize Gene Expression Values over Time

Table 1

Overview of methods under consideration.

Method	GX	Pseudo-	If using pseudo-genes, which summary score is used
	Values^1	Genes^2
Sign Avg & LASSO/CD		√	Sign average of a gene’s expression over time.
Sign Avg &TGDR		√	Sign average of a gene’s expression over time.
Mean & LASSO/CD		√	Mean of a gene’s expression value over time.
Mean & TGDR		√	Mean of a gene’s expression value over time.
Median & LASSO/CD		√	Median of a gene’s expression value over time.
Median & TGDR		√	Median of a gene’s expression value over time.
PC1 & LASSO/CD		√	First principal component of a gene’s expression value over time
PC1 & TGDR		√	First principal component of a gene’s expression over time.
EDGE	√
limma	√
LASSO/CD separately	√
TGDR separately	√
glmmLASSO	√

GX values represent actual expression values.
² Pseudogenes are generated to summarize expression values across time.