. 2002 May;68(5):2188–2197. doi: 10.1128/AEM.68.5.2188-2197.2002

TABLE 4.

Analysis of assumed t-distributed RS and ES at the Kall gauge for independence from each other, using the one-sided t test for two spot checks with different variances (1997 data)

Parameter	RS (n = 26)			ES (n = 11)			t test t (empirical)	df (empirical)	P(α) (one sided)^a
Parameter	Arithmetic mean	Maximum	SD	Arithmetic mean	Maximum	SD	t test t (empirical)	df (empirical)	P(α) (one sided)^a
Turbidity (NTU)	3.57	10.20	2.53	28.25	54.30	15.99	5.092	10.254	0.000^b
pH	7.43	7.70	0.15	7.05	7.40	0.17	6.362	18.468	0.000^c
Runoff (liters/s)	290.78	1,783.32	363.55	1,276.78	2,732.00	948.54	5.685	11.515	0.000^b
Nitrate (mg/liter)	13.94	22.20	3.15	10.58	15.40	4.16	2.405	16.061	0.014^c
Nitrite (mg/liter)	0.01	0.09	0.02	0.07	0.13	0.03	5.169	16.120	0.000^b
Ammonia (mg/liter)	0.04	0.19	0.06	0.24	0.46	0.18	3.632	11.167	0.002^b
Total phosphorus (mg/liter)	0.01	0.10	0.03	0.08	0.30	0.10	2.299	10.969	0.022^b
Borate (mg/liter)	0.07	0.11	0.02	0.11	0.18	0.03	3.961	15.217	0.001^b
CC 20°C (CFU/ml)	3,623.50	46,300.00	9,864.96	49,109.09	114,000.00	30,359.10	4.862	11.084	0.000^b
CC 37°C (CFU/ml)	787.42	12,000.00	2,321.39	10,797.27	37,000.00	11,589.17	2.841	10.409	0.009^b
E. coli (CFU/100 ml)	929.38	11,000.00	2,316.65	1,340.91	3,800.00	1,040.45	0.745	36.958	0.230
Coliforms (CFU/100 ml)	27,396.38	400,000.00	85,304.60	20,890.91	63,000.00	21,107.60	0.363	31.788	0.359
Fecal streptococci (CFU/100 ml)	601.38	11,000.00	2,156.15	919.09	4,600.00	1,259.27	0.559	33.771	0.290
C. perfringens (CFU/100 ml)	37.96	198.00	48.28	316.00	900.00	240.12	3.808	10.412	0.002^b
Giardia (cysts/100 liters)	1.67	11.10	2.55	3.08	21.00	6.27	0.722	11.708	0.243
Cryptosporidium (oocysts/100 liters)	3.03	10.30	2.80	22.32	65.60	17.75	3.585	10.253	0.002^b

Values were considered significantly different if the P(α) value was <0.05.

The ES values were significantly greater than the RS values.

The ES values were significantly less than the RS values.