Temporal Aspects of Surface Water Quality Variation Using Robust Statistical Tools

Table 2

Dry season classification functions for discriminant analysis (DA) of parameters in mg/L except for temperature, conductivity, and pH.

Variables	Standard mode		Forward stepwise mode		Backward stepwise mode
	Lambda	𝑃 value	Lambda	𝑃 value	Lambda	𝑃 value
DO	0.623	<0.0001	0.623	<0.0001	0.623	<0.0001
BOD5	0.793	<0.0001
COD	0.699	<0.0001	0.699	<0.0001	0.699	<0.0001
SS	0.994	0.508
pH	0.893	0.004	0.893	0.004	0.893	0.004
NH3	0.725	<0.0001	0.725	<0.0001	0.725	<0.0001
Temperature	0.954	0.064
Conductivity	0.867	0.001
Salinity	0.776	<0.0001
Turbidity	0.999	0.811
DS	0.891	0.004
TS	0.930	0.021
NO3	0.988	0.339
Cl	0.985	0.296	0.985	0.296	0.985	0.296
PO4	0.991	0.427
Wilks’ lambda	0.37		0.42		0.42
Chi-square	381.57		46.60		46.60
𝑃level	<0.0001		<0.0001		<0.0001