YSI 85 - Manual (Page 32)

Discussion of Measurement Errors Section 11
YSI, Incorporated Model 85 28
TYPE 3 ERRORS
A. Altitude:
A 1000-foot change in altitude is equal to an error of approximately 3% at the 10
mg/l level.
B. Humidity:
Errors occur if calibration is performed at less than 100% humidity. The error varies
with the temperature as follows:
TEMPERATURE ERROR
0
o
C 0.02 mg/l
10
o
C 0.05 mg/l
20
o
C 0.12 mg/l
30
o
C 0.27 mg/l
40
o
C 0.68 mg/l
APPROXIMATING THE ERROR
It is unlikely that the actual error in any measurement will be the maximum possible error. A better
error approximation is obtained using a root mean squared (r.m.s.) calculation:
r.m.s. error = ±[1a
2
+ 1b
2
+ 2a
2
+ 2b
2
+ 3a
2
+ 3b
2
]
½
mg/l