df<-read.csv(header=T, text="
ID, Group, Hemi, total, wealth
100, 0, 0, 39, 1.99
100, 0, 1, 44, 1.99
101, 0, 0, 38, 2.01
101, 0, 1, 23, 2.01
102, 0, 0, 22, 22.1
102, 0, 1, 23, 22.1
200, 1, 0, 33, 80.1
200, 1, 1, 23, 80.1
202, 1, 0, 18, 12.1
202, 1, 1, 28, 12.1")
#hemi=0 for left, hemi=1 for right
df$hemi<-as.factor(df$hemi)
df$group<-as.factor(df$group)
df$ID<-as.factor(df$ID)

#Fitting the ANCOVA
ezANOVA(data = df, between_covariates = wealth,
 dv=total, wid=ID, within=hemi, between=Group)