Chart 1 Anthropometric data quality indicators

Completeness

Target population coverage (%)

Percentage of the number of children with a SISVAN nutritional status record, divided by the SUS under 5 user population, multiplied by 100.

The SUS user population was obtained by subtracting the total population (estimated by the IBGE) from the population covered by private health insurance (obtained from the ANS).

All children with a SISVAN nutritional status record.

Completeness of date of birth (%)

Percentage of the number of records with the full month and year of birth, divided by the total number of SISVAN child records, multiplied by 100.

All SISVAN nutritional status follow-up records.

Completeness of anthropometric measurements (%)

Percentage of the number of records with completed weight and lengtht/height measurements, divided by the total number of SISVAN child records, multiplied by 100.

All SISVAN nutritional status follow-up records.

Sex ratio

Sex ratio

Ratio of the number of boys divided by the number of girls.

The ratio expected for the Brazilian population under the age of 5, estimated by the IBGE, was used as a reference for comparison purposes.

All SISVAN nutritional status follow-up records.

Age distribution

Age dissimilarity index (in months)

The Myers’ unblended dissimilarity index was analysed to identify the percentage of records deviating from an equal distribution of age in months (0–59).

It was calculated by the sum of the observed percentages subtracted by the expected percentages, divided by 2.

The dissimilarity index varies between 0 and 90, with 0 being the ideal value.

All records with a complete month and year of birth.

Digit preference for lengtht/height and weight

Dissimilarity index for the last digits for lengtht/height (cm) and weight (kg)

The Myers’ unblended dissimilarity index was analysed to identify the percentage of records deviating from an uniform distribution of last lengtht/height and weight digits.

It was calculated by the sum of the observed percentages, subtracted by the expected percentages, divided by 2.

The dissimilarity index varies between 0 and 90, with 0 being the ideal value.

All records with weight and/or height information.

Implausible z-score values

Percentage of implausible z-scores for each anthropometric index (%)

Percentage of the number of records with implausible z-score values, divided by the total number of SISVAN child records, multiplied by 100.

Using the WHO “anthro” flagging system, implausible Z-score values were detected according to plausibility criteria (WHO, 1995): HAZ (-6, + 6), WHZ (-5, + 5), WAZ (-6, + 5) and B/AZ (-5, + 5).

All records with date of birth, weight, and/or lengtht/height information.

Dispersion of z-score values

Standard deviation of plausible z-score values for each anthropometric index

Standard deviation was calculated using the formula below:

\(\:\sqrt{\frac{{\sum\:}_{\text{i}=1}^{\text{n}}{\left({y}_{i}-\stackrel{-}{\text{y}}\right)}^{2}}{\text{n}-1}}\)

Where n is the total number of observations, Yi is each database value, and \(\:\stackrel{-}{\text{y}}\) overall mean of the variable.

All records with biologically plausible Z-score values for the anthropometric index of interest.