Table 4.

Two-sample t-test, interclass correlation coefficients (ICC), and R² results for each element of interest. Values were obtained using a 95% confidence level and a two-way agreement model. Bolded text indicates statistical significance.

	Arizona
	As	Ni	Ca	Cu	Cr	Ba	Fe	Zn	Pb	Mn	K
ICC coefficients	0.87	0.29	0.87	0.98	0.09	0.13	0.17	0.91	0.92	0.64	0.02
P-value	0.45	0	0.04	0.42	0	0.17	0	0.24	0.97	0.33	0
T- Statistic	0.74	−4.93	2.11	0.81	−14.43	1.39	−14.32	1.16	0.04	0.99	26.08
R2	0.76	0.08	0.76	0.95	0.01	0.02	0.03	0.82	0.83	0.42	0
	New York
	As	Ni	V	Cu	Cr	Al	Fe	Zn	Pb	Mn
ICC coefficients	0.54	0.52	0.53	0.73	0.63	0.40	0.81	0.99	0.91	0.95
P-value	0.11	0.22	0	0.38	0.02	0	0	0.31	0.90	0.47
T- Statistic	1.62	1.24	22.09	−0.89	−2.39	−11.6	−13.9	1	0.12	0.72
R2	0.29	0.27	0.28	0.54	0.40	0.16	0.66	0.98	0.83	0.92