394-395 / 620
Table 2
T
stat
p
-value
709.5 mg/100g
Value is listed as
"informational" only
Determined by
NIST
T
stat
=
4.122
where: = mean of the differences between measured results and reference value
4.2
sd = standard deviation of the differences between results and reference value
3.53
n
= number of replicate analyses of SRM
12
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 and reference value
n
= number of replicate analyses of SRM
Day
Chloride (mg/100g)
Difference (mg/100g)
1
717.4
7.4
1
715.0
5.0
2
699.9
10.1
2
712.1
2.1
3
715.7
5.7
3
710.1
0.1
4
703.2
6.8
4
707.7
2.3
5
709.9
0.1
5
701.2
8.8
6
710.3
0.3
6
712.1
2.1
Average (mg/100g)
709.5
4.2
Standard Deviation
5.64
3.53
One-way ANOVA: Chloride (mg/100g) versus Day
Source DF SS MS F P
Day 5 207.2 41.4 1.75 0.258
Error 6 142.4 23.7
Total 11 349.6
S = 4.872 R-Sq = 59.26% R-Sq(adj) = 25.31%
Individual 95% CIs For Mean Based on
Pooled StDev
Level N Mean StDev ----+---------+---------+---------+-----
1 2 716.20 1.67 (-----------*-----------)
2 2 705.99 8.62 (-----------*-----------)
3 2 712.88 4.00 (-----------*-----------)
4 2 705.44 3.13 (-----------*-----------)
5 2 705.55 6.15 (-----------*-----------)
6 2 711.20 1.27 (-----------*-----------)
----+---------+---------+---------+-----
700.0 707.0 714.0 721.0
Pooled StDev = 4.87
Accuracy - Analytical bias compared to reference material
Certified Reference Material
Measured Results
CRM Product
Analyte
Certified value
Uncertai
nty
NIST 1849a
Chloride
N/A
710 mg/100g
using instrumental
neutron activation
analysis (INAA)
Certified
range
Concentration
N/A
#NUM!
Difference
from
Bias
Confidence interval
-
#NUM!
n
/
sd
d
d
d
n
t
crit
sd
n
t
crit
sd
crit
t
10
5
0
-5
-10
99
90
50
10
1
Residual
Percent
715.0
712.5
710.0
707.5
705.0
5.0
2.5
0.0
-2.5
-5.0
Fitted Value
Residual
5.0
2.5
0.0
-2.5
-5.0
4
3
2
1
0
Residual
Frequency
12 11 10 9 8 7 6 5 4 3 2 1
5.0
2.5
0.0
-2.5
-5.0
Observation Order
Residual
Normal Probability Plot
Versus Fits
Histogram
Versus Order
Residual Plots for Chloride (mg/100g)
Chlor-04 MEF Form
FOR ERP USE ONLY
DO NOT DISTRIBUTE