Table 3.

ANOVA results for S/N ratio and gray value differences for ROIs 1–9: factor sum of squares (SS), pure sum of squares (SS′), degree of freedom (DOF), variance (V), percentage of each factor (P), effective number of replication of experiment (${\mathrm{N}}_{\text{eff}}$) and error variance (${\mathrm{V}}_{\mathrm{e}}$).

Factor	SS	DOF	V	SS′	P (%)
A	0.01	1 a	0.01
B	4.15	1 a	4.15
C	120	1	120	118	42.7
D	13.5	1	13.5	11.5	4.2
E	54.8	1	54.8	52.8	19
F	13.6	1	13.6	11.6	4.2
G	84.5	1	84.5	82.4	29.8
Total					100

^aError terms in ANOVA analysis.

${\mathrm{F}}_{0.05;1,2}=18.51$ (F‐ratio at 95% confidence); ${\mathrm{V}}_{\mathrm{e}}=({\text{SS}}_{\mathrm{A}}+{\text{SS}}_{\mathrm{B}})/({\text{DOF}}_{\mathrm{A}}+{\text{DPF}}_{\mathrm{B}})(\text{error}\hspace{0.17em}\text{variance});{\mathrm{N}}_{\text{eff}}=8/(1+5)$ (effective number of replication of experiment).