Table 2.

Bivariate and multivariate regression analyses

Dependent	Independent	rs-S	rs-US	Dependent	Independent	rs-S	rs-US
Bivariate (Spearman rank correlation, SRC)
Mass	Storage	0.11	− 0.22	Total lipids	Storage	0.58*	0.66*
Area	Storage	0.02	0.17	Tocopherols	Storage	0.56*	0.81*
Volume	Storage	0.02	0.17	Tocotrienols	Storage	− 0.10	− 0.11
Moisture	Storage	0.26	− 0.54*	Total tocols	Storage	0.53*	0.81*
Protein	Storage	− 0.48*	− 0.05	SFA	Storage	0.29	− 0.29
Carbohydrates	Storage	− 0.41*	− 0.57*	MUFA	Storage	− 0.24	0.04
Ash	Storage	0.42*	0.03	PUFA	Storage	0.39	0.00

Dependent	Independent	Shell	β	R2	p	RMSE
Multivariate (Stepwise linear regression, SLR)
Total lipids	Carbohydrates	Split	− 0.95	0.90	< 0.001	0.52
Total tocols	PUFA	Split	0.83	0.68	0.003	3.60
MUFA	Area (M1)	Split	1.24	0.71	0.002	2.50
	PUFA (M2)	Split	− 0.61	0.17Δ	0.040
Total lipids	Carbohydrates	Unsplit	− 0.97	0.93	0.001	0.80
Total tocols	Total lipids	Unsplit	0.87	0.76	0.001	2.54
MUFA	Area (M1)	Unsplit	0.66	0.43	0.001	2.10
	Moisture (M2)	Unsplit	− 0.59	0.34Δ	0.002

Chemical composition data from kerman pistachio kernels

Statistically significant (p-trend ≤ 0.04)

SLR model of one (M1) and two (M2) factors, Monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids, Spearman’s coefficient (rs) for split (rs-S) and unsplit (rs-US) samples, determination coefficient (R²), incremental value (Δ from M1), root mean square error (RMSE)