118-119 / 164
Table 2
Nominal
T
stat
p
-value
182.2
1.8
182.3
1.7
185.6
-1.6
183.9
0.1
179.9
4.1
181.1
2.9
180.1
3.9
179.4
4.6
176.8
7.2
Mean
181.3
2.7
SD
2.6
2.6
T
stat
=
where: = mean of the differences between measured results and reference value
sd = standard deviation of the differences between results and reference value
n
= number of replicate analyses of SRM
H
0
: = 0, The null hypothesis is that there is no difference between the measured results and the certified value:
p
-value: is the probability (at the 95% levels of confidence) of obtaining the test statistic assuming that the null hypothesis is true.
p
-value < 0.05 indicate a difference of statistical signifance between measured results and SRM.
95% confidence interval: The true population of the measured value expected to fall within the confidence interval estimate 95% of the time.
lower limit = mean -
upper limit = mean +
where: = critical values of the t-distribution
sd = standard deviation of the differences between results an reference value
n
= number of replicate analyses of SRM
0.013
179.3
-2.7
Uncertainty Certified range Concentration
Difference from
certified value
Confidence interval
- 183.3
10
174 - 194
3.159
SRM 1849a
Tryptophan
184
Bias
Accuracy - Analytical bias compared to reference material
Certified Reference Material
Measured Results
CRM product
Analyte
Certified value
n
/
sd
d
d
d
n
t
crit
sd
n
t
crit
sd
crit
t
SPIFAN ERP Checklist v1.0
AMINO-02 (FEBRUARY 2017) - MEF FORM
FOR ERP USE ONLY
DO NOT DISTRIBUTE
22