Metrological issues for food consumption data.

Max FeinbergINRA. Mét@risk

feinberg@inapg.inra.fr

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” ?