Metrological issues for food consumption data. Max Feinberg INRA. Mét@risk [email protected]...
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Transcript of Metrological issues for food consumption data. Max Feinberg INRA. Mét@risk [email protected]...
Max Feinberg
Nutritional epidemiology
Using nutritional measurements to study the potential link between nutrition and disease and find methods to prevent the disease.
The best the measurements, the best the decisions…
Max Feinberg
General nutritional measurement
i : individual (household)
j : food (group)
Consumptions
cij
Con
ten
ts qj
A)(iN
aA i
i
Weig
hts p
i
Foods
Con
sum
ers
i
jjij
i p
qc
a
Exp
osu
res
= ai
Food
s
Max Feinberg
Consumption measurement
Consumptions
cij
Weig
hts p
i
Foods
Con
sum
ers
Max Feinberg
Consumption measurements (2)
24-hour Recall (24R)Attempt to define and quantify food intake during a specific day.
Dietary Records (DRs)Detailed descriptions of types and amounts of foods and beverages consumed, meal by meal, over a prescribed period (3-7 days).
Food Frequency Questionnaires (FFQ)Long-term diet over months or years, not just a few days.
Household Budget Survey (HBS)Estimation of the average consumption of a population based on point estimates of food consumptions.
Total Diet Study (TDS)Estimation of consumer exposure to contaminants based on the analysis of foods « as consumed ».
…
Max Feinberg
Survey reduction
i : individualsk : households
j : foods
Individualconsumptions
cij
Weig
hts p
i
Direct methods
Degradation ??
Householdconsumptions
mkj
Purchasing panels
Consumptions
hj
National budget
Uncertainty and variability
A proposal to evaluatenutritional measurement
quality
Max Feinberg
International Vocabulary of Metrology
Metrology: field of knowledge concerned with measurement.
Metrology includes all theoretical and practical aspects of measurement, whichever the measurement uncertainty and field of application.
Measurand: quantity intended to be measured.
Uncertainty (of measurement): parameter that characterizes the dispersion of the quantity values that are being attributed to a measurand, based on the information used.
Max Feinberg
Analogy with chemical measurement
95% of replicates in the interval
sy 96.1
Does this interval
representuncertainty?
Measurandy
+
1
)( 2
n
yys i
n
yy i
Y T
ReportedValue Y
+ True Value T
Max Feinberg
Sources of uncertainty in analysis
PersonnelMethod
Environment
Equipment
Traceability
Sampling
Samples handling
Result +Uncertainty
Calibration
Instrument
Material
Method
Manpower
Milieu
Max Feinberg
Vary sources of uncertainty
B1
B2
B3
yij1y+
Day 1
2y +
3y+
Day 3
Day 2
+
Day 1
Day 2
Day 3
B1
B2
B3
Standard deviation of:reproducibility
22BrR sss
Max Feinberg
Standard and expanded uncertainty
ReportedValue
+ True Value
Composed standard uncertainty
22)( Brc ssYu
Expanded uncertainty
95% of the future measurements
U = kuc(Y) p = 95% k = 2 p = 99% k = 3
Y T
Measurand
Max Feinberg
Measurement +
Uncertainty
Grouping
Food
Inquirer
Individual
Panel Study
Competence
Weight
Age,Social category, …
Culture ?
Selection
Size
Location Duration
Naming
Grouping
Uncertainty sources for nutritional measurements
Instrument
Material
MethodManpower
Milieu
Max Feinberg
Consumption pattern
Use multivariate techniques to identify consumption systems
Consumptionpattern
Consumptionsystem
Individual
Uncertainty
+
+
=
Variability
Max Feinberg
Simulated consumption systems
0% 20% 40% 60% 80% 100%
Food groups (% Weight)
System 1
Ind 1
Ind 2
Ind 3
Ind 4
System 2
Ind 5
Ind 6
Ind 7
Ind 8
Fruits
Vegetables
Meat
Cereals
Dairy
Fish
Max Feinberg
Conclusions
Needs for harmonisation.Data collection procedures.Data evaluation.Identification of bias.How far are methods complementary?
A proposal:use uncertainty-variability approach to organise harmonisation.A new discipline: “Consumetrics” ?