2.1: Anthropometric Indicators Measurement Guide - Linkages Project

REFERENCES PART 9.
Weight (kg) for age distribution by standard deviation for boys
Age Group
(months)
Lower
S.D.
-3
S.D.
-2
S.D.
-1
S.D.
Mean
+1
S.D.
+2
S.D.
+3
S.D.
Upper
S.D.
12
13
14
15
16
17
18
19
20
21
22
23
24
1.0
1.0
1.1
1.1
1.1
1.1
1.2
1.2
1.2
1.3
1.3
1.3
1.1
7.1
7.3
7.5
7.6
7.7
7.8
7.9
8.0
8.1
8.3
8.4
8.5
9.0
8.1
8.3
8.5
8.7
8.8
9.0
9.1
9.2
9.4
9.5
9.7
9.8
10.1
9.1
9.4
9.6
9.8
10.0
10.1
10.3
10.5
10.6
10.8
10.9
11.1
11.2
10.2
10.4
10.7
10.9
11.1
11.3
11.5
11.7
11.8
12.0
12.2
12.4
12.3
11.3
11.5
11.8
12.0
12.3
12.5
12.7
12.9
13.1
13.3
13.5
13.7
14.0
12.4
12.7
13.0
13.2
13.5
13.7
13.9
14.1
14.4
14.6
14.8
15.0
15.7
13.5
13.8
14.1
14.4
14.7
14.9
15.2
15.4
15.6
15.8
16.0
16.2
17.4
1.1
1.1
1.2
1.2
1.2
1.2
1.2
1.2
1.3
1.3
1.3
1.3
1.7
standards for weight-for-age we see that
the “average” healthy boy of 19 months
should weigh 11.7 kilograms. Since this
child is obviously under the mean of 11.7
kilograms, we need to check the lower
standard deviation value (remember: with
weight-for-age the lower and upper
standard deviations might differ!). It is 1.2
kilograms. With these two pieces of
information, we can calculate the Z-score
of a child’s weight-for-age, using the
following procedures:
Subtract the mean weight from the actual
weight of the child. The results in this case
will be negative.
Example: 9.8 kg - 11.7 kg = -1.9
Divide the result by the standard deviation
for the child’s age and gender.
Example: -1.9 / 1.2 sd = -1.58 SD units
The resulting number is the Z-score for
that child.
Example: The Z-score for a 19 month old
boy who weighs 9.8 kg is -1.58 standard
deviation units.
This procedure can be repeated with the
appropriate graphs or tables to calculate
the Z-scores for length-for-age and
weight-for-height.
Percent of the Median
Procedure
For this example, we will assume we have
just measured the length of a girl who is
24 months old. This girl is 64.9 cm long.
We want to use percentages of the median
to compare her to the reference standards.
Using the percentile distribution for the
appropriate index (weight-for-age, lengthfor-age
or weight-for-length) and sex, find
the measurement that corresponds to the
50th percentile (remember the 50th
percentile is the same as the median).
Example: From a table of reference
values we learn that the 50th percentile
length measurement for a 24 month old
girl is 86.5 cm.
Divide the measurement of the individual child
by the appropriate median measurement.
Example: Our girl is 64.9 cm.
The median value for girls is 86.5 cm.
64.9 cm / 86.5 cm = .75
Multiply this fraction by 100, to convert it
to a percentage.
Example: 0.75 x 100 = 75%
9.
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