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VIDAS LMX – Summary 2012 v01
Results according to general protocol
Fish products
(66)
Positive reference method
(R+)
Negative reference method
(R-)
Positive alternative method
(A+)
Positive agreement (A+/R+)
PA = 27
Positive deviation (R-/A+)
PD = 2
Negative alternative method
(A-)
Negative deviation (A-/R+)
ND = 2
Negative agreement (A-/R-)
NA = 35
Vegetables (71)
Positive reference method
(R+)
Negative reference method
(R-)
Positive alternative method
(A+)
Positive agreement (A+/R+)
PA = 22
Positive deviation (R-/A+)
PD = 7
Negative alternative method
(A-)
Negative deviation (A-/R+)
ND = 3
Negative agreement (A-/R-)
NA = 39
Environment (60)
Positive reference method
(R+)
Negative reference method
(R-)
Positive alternative method
(A+)
Positive agreement (A+/R+)
PA = 24
Positive deviation (R-/A+)
PD = 2
Negative alternative method
(A-)
Negative deviation (A-/R+)
ND = 4
Negative agreement (A-/R-)
NA = 32
2.1.4 Calculation of relative accuracy (AC), relative specificity (SP) and relative
sensitivity (SE)
All previous results were used to calculate the relative accuracy, relative sensitivity and relative specificity for each
category, according to the EN ISO 16140 standard.
The results obtained with VIDAS LMX + confirmations are summarised in the table below:
Category
PA NA ND PD
Sum
N
Relative accuracy
AC (%)
[100x(PA+NA])/N
N+
PA + ND
Relative sensitivity
SE (%)
[100xPA]/N+
N-
NA + PD
Relative specificity
SP (%)
[100xNA]/N-
Meat products
24
32
3
3
62
90.3
27
88.9
35
91.4
Dairy
products
including raw milk
cheeses
56
58
6
5
125
91.2
62
90.3
63
92.1
Fish products
27
35
2
2
66
93.9
29
93.1
37
94.6
Vegetables
22
39
3
7
71
85.9
25
88.0
46
84.8
Environment
24
30
4
2
60
90.0
28
85.7
32
93.8
TOTAL
153 194 18 19
384
90.4
171
89.5
213
91.1
The percentage values of the alternative method calculated for the following three criteria according to the EN ISO
16140 standard were :
General protocol + specific protocol
All products (all Human foods and
environmental samples)
Reminder General protocol
All Human foods without raw milk
cheeses and environmental samples
Relative accuracy
:
AC
90.4 %
91.3 %
Relative specificity
:
SP
91.1 %
92.2 %
Relative sensitivity
:
SE
89.5 %
90.2 %
The AFNOR Technical Board asks the sensitivity of both methods to be calculated with consideration of all the
confirmed positives (this includes the additional positives of the alternative method) :
Alternative method
(PA + PD) / (PA + PD + ND)
Reference method
(PA + ND) / (PA + PD + ND)
All products
(
General protocol + specific protocol
)
90.5 %
90.0 %
All Human foods without raw milk cheeses and
environmental samples
(Reminder General protocol)
91.1 %
91.1 %