Metrohm tiBase 1.1 - Manual (Page 61)

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2 General program functions
tiBase 1.1
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Type number, value range: 1 ... n. Direct entry as number or as formula
providing a number. If the type of value is non-permitted, then the result
will become invalid. The number of independent samplings for calculat-
ing the standard deviation, reduced by the number of adjusted parame-
ters for the model to which the standard deviation refers, must be speci-
fied as degrees of freedom (Degrees of freedom = Number of samplings
−
Number of parameters).
Examples
Tinv(0.95; 9) = 2.26 : With a 10-fold determination (e.g. of a titer) half
the interval length corresponds to 2.26 times the standard deviation.
Calculation of the confidence interval for a mean value of sam-
pling: A variance-homogenous sampling with a range n for a normally
distributed quantity with an expected value µ has the mean value x
m
, the
standard deviation s and the freedom degrees v = n − 1. Half the interval
length t
s
⋅ s/√ n then indicates how high the absolute difference between
the mean value x
m
and the expected value µ maximally is within the given
probability. The confidence interval is the full interval length, centered
to the mean value: µ = x
m
± t
s
⋅ s/√ n.
Titer determination: 0.991, 1.021, 0.995, 1.003, 1.007, 0.993, 0.998,
1.015, 1.003, 0.985
Mean value = 1.001
Standard deviation = 0.0111
Student's t-quantiles for a probability of 95% = 2.26
Confidence interval of the titer = 1.001 ± 0.008
2.4.4.6 Date/time functions
2.4.4.6.1 Time()
Dialog window: Formula editor ▶ Operators/Functions
Syntax
y = Time()
Gives the current date and the current time.
Parameters
none
Return value
Current date and current time in the format yyyy-mm-dd hh:mm:ss
UTC ±xx