First NENALAB Meeting, 9-11 June 2020 (online)

1. GLOSOLAN
Global Profeciency Testing 2019
Mr. Christian Hartmann (IRD France, researcher)
Mrs. Nopmanee Suvannang (GLOSOLAN chair person)
Mrs. Lucrezia Caon (GSP NENA & GLOSOLAN coordinator)
christian.hartmann@ird.fr

2. Inter Laboratory Comparison (ILC)
similar samples analysed by different labs
Testing samples prepared
using pure chemicals (formulation)
==> you know the analytical
results that labs should to provide.
Proficiency Testing (PT)
Introduction (1/3):

3. NO !
==> real soils must be collected and ‘prepared’.
Results can be affected by
- problem of homogeneity that needs to be carefuly considered
- impacts of soil constituents (clay type/amount, oxides, OM, etc) during analysis.
Proficiency testing
Inter Laboratory Comparison (ILC)
similar samples analysed by different labs
Possible to use artificially formulated soils ?
Introduction (2/3):

4. Introduction (3/3):
With real soils (not formulated)
the assigned value* is calculated by
using the results provided by the participants.
* best available estimate of the true value.
Inter Laboratory Comparison (ILC)
similar samples analysed by different labs

5. 3 different soils: A, B, C (provided by Mexico)
100 g of each soil sample sent to participants
Participants had to separate them in 3 sub-samples
Analyse each sub sample
No special treatment compared to the ‘ordinary’ samples
GLOSOLAN ‘PT’ 2019 (1/2):

6. 10 parameters, 14 methods
pH suspension in water
SOC sulfo-chromic oxydation (WB), combustion
N Kjeldhal, combustion
P Olsen, Bray1, Bray 2
K exch in amonium acetate
Ca exch in amonium acetate
Mg exch in amonium acetate
Na exch in amonium acetate
EC electrical conductivity in suspension
CaCO3 calcimetry
GLOSOLAN ‘PT’ 2019 (1/2):

7. For you (lab managers): performance assessment.
PT objectives(1/2):

8. 8
What is good performance?
LOW performance
(high dispersion)

9. 9
What is good performance?
LOW performance
(high dispersion)
Z score
Z <1
1< Z <2 satisfactory

10. 10
What is good performance?
LOW performance
(high dispersion)
Z score
Z <1
1< Z <2
2 <Z <3
satisfactory
questionable

11. 11
What is good performance?
LOW performance
(high dispersion)
Z score
Z <1
1< Z <2
2 <Z <3
satisfactory
Z >3 UN-satisfactory
questionable

12. 12
What is good performance?
HIGH performance
(limited dispersion)
Z <1

13. 13
What is good performance?
Z <1
HIGH performance
(limited dispersion)

14. 14
What is good performance?
Z <1
It results from daily work
& regular training.
HIGH performance
(limited dispersion)

15. For you (lab managers): performance assessment.
PT objectives(1/2):

16. For you (lab managers): performance assessment.
For GLOSOLAN:
1. As no real certified reference soil material exists, it is
the best possible estimation of an assigned value
==> average of all results provided by participants
PT objectives(2/2):

17. For you (lab managers): performance assessment.
For GLOSOLAN:
1. As no real certified reference soil material exists, it is
the best possible estimation of an assigned value.
2. measure the ‘global’ dispersion, i.e. uncertainty
(standard deviation) of the assigned value.
(uncertainty is necessary to make scientific conclusion)
PT objectives(2/2):

18. For you (lab managers): performance assessment.
For GLOSOLAN:
1. As no real certified reference soil material exists, it is
the best possible estimation of an assigned value.
2. measure the ‘global’ dispersion (i.e. uncertainty of
the assigned value on a world basis).
3. Identify low performing labs to suggest corrective
actions and help them improving their performance.
PT objectives(2/2):

19. th
Outliers

20. Different ways
to present the results
1. Quality charts

21. 1. Quality charts
pH

22. A
B
C
pH
6
8
4
Lab number
average
average + 2sd
average + 3sd

23. A
B
C
pH
6
8
4
Lab number
average
average + 2sd
average + 3sd
Results
Each lab: 3 rep
==> good precision!

24. A
B
C
6
8
4
Lab number
average
average + 2sd
average + 3sd
low precision
accurate but…

25. A
B
C
6
8
4
Lab number
What is the
general
picture?

26. pH
6
8
4
5.32 (sd=0.24)
5.18 (sd=0.31)
6.55 (sd=0.22)

27. pH
6
8
4
[Dispersion:
1 unit pH

28. Organic carbon
(Walkley & Black)

29. OC_WB
(%)
0
2
4
6
0
2
4
6

30. OC_WB
(%)
Dispersion:
1% OC0
2
4
6
0
2
4
6
Dispersion:
1% OC
Dispersion:
2% OC

31. Many
outliers
0
2
4
6
0
2
4
6

32. OC_WB
(%)
0
2
4
6
0
2
4
6

33. OC_WB
(%)
0
2
4
6
0
2
4
6
It results from daily work
& regular training.

34. 0
2
4
6
0
2
4
6

35. Organic carbon
(COMBUSTION)

36. OC
combustion
(%)
0
2
4
6
0
2
4
6
A
B
C

37. OC
combustion
(%)
0
2
4
6
0
2
4
6
A
B
C

38. OC
combustion
(%)
0
2
4
6
0
2
4
6
A
B
C
Dispersion:
1% OC

39. OC
combustion
(%)
0
2
4
6
0
2
4
6
A
B
C
Dispersion:
1% OC
Still
many
outliers
!

40. OC
combustion
(%)
0
2
4
6
0
2
4
6
A
B
C
Dispersion:
1% OC
Still
many
outliers
!

41. Different ways
to present the results
1. Quality charts
2. Z score
(statistical comparision of performances)

42. The same results presented differently:

43. The same results presented differently:

44. Problem of pHmeter calibration ?
acidic acidic neutral

45. The same results presented differently:

46. Different ways
to present the results
1. Quality charts
2. Z score (to compare performances)
3. Individual Z score (each lab performance)

48. For you (lab managers): performance assessment.
For global soil management:
1. Each country can control its reference laboratories +
get a stock of reference soils with the best possible
estimation of an assigned value.
2. International institutions can know the uncertainty
of their data to make relevant models or decisions.
3. Labs can discover their weak points and improve
kind to GLOSOLAN and global partnership.
PT is necessary:

49. Thanks for your attention