---
title: "Anthropometric measurements standardisation test"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Anthropometric measurements standardisation test}
  %\VignetteEngine{knitr::rmarkdown}
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---

```{r, include = FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
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```

```{r setup, echo = FALSE}
library(anthrocheckr)
```

The survey personnel should go through theoretical discussions and demonstrations on how to perform the anthropometric measurements. This should then be followed by practical demonstration of the measurement techniques, measurement readings and recording ideally with a large number of children particularly if there is a large number of survey personnel. Once all personnel have had the opportunity to adequately practice their measurement and recording techniques, a standardisation test or exercise must be carried out. This chapter provides detailed instructions on how to carry out an anthropometric measurement standardisation test as part of a training process in preparation for a nutrition survey.

## Objectives {#sec-standardisation-test-objectives}

The standardisation test evaluates the **precision** and the **accuracy** of the measurements taken by each survey personnel.

The **accuracy** of measurements taken by survey personnel is determined by how close they are to the true value with repeated measurements. On the other hand, the **precision** of measurements taken by survey personnel is determined by how similar the values are of repeated measurements made. In preparation for a nutrition survey while the survey personnel are in training, the aim is for survey personnel to be *highly accurate* and *highly precise* with their anthropometric measurements.

![Relationship between accuracy and precision](../man/figures/accuracyPrecision.png)

## Mechanics {#sec-standardisation-test-mechanics}

The general process of the standardisation test is for each survey personnel to take measurements of at least 10 children 6-59 months, twice, with an interval of time between the first and second measurements.

### Test parameters {#sec-standardisation-test-parameters}

The following test parameters need to be followed when conducting an anthropometric standardisation test:

1. The same type of equipment must be used both during the standardisation test and the survey

2. Each child is measured with the same equipment

3. The supervisor must observe how measurements are being taken

4. Survey personnel measurements are compared to the reference (supervisor) values

5. Survey personnel measurements are compared to the repeated measures taken (intra-observer)

### Test organisation and requirements {#sec-standardisation-test-requirements}

The following test organisation and requirements need to be met in order to conduct a credible standardisation test:

1. Spacious and shady area

2. Healthy children between 6 and 59 months or according to the age group targeted by the survey

3. Incentives provided for the mother and children 

3. Survey personnel are grouped into pairs, but each personnel will carry out the measurements in turn

4. There should only be one pair of survey personnel per child at any time during the test

5. Each survey personnel is given a unique ID. For example if there are 20 survey personnel, a unique ID from 1 to 20 is given to each survey personnel. The supervisor’s ID is always 0.

6. Each measurement station should have a height board, weighing scale and a MUAC tape

7. Each child must remain with their mother in a fixed station with a unique ID number. For example if there are 10 mother and children pairs, a unique ID from 1 to 10 is given to each pair

8. It is not allowed for pairs of survey personnel to speak with other pairs during the test


### Timeframe {#sec-standardisation-test-timeframe}

In order to follow the test parameters specified above and organise the test appropriately, a considerable amount of time needs to be set aside for conducting the test.

For a survey team of about 20 survey personnel, the test can be carried out in 2 half-days such that half of the survey personnel (first half of each team) measures 10 children in the morning and the other half (second half of each team) measures the same 10 children in the afternoon.

It would be possible to have a different set of 10 children for the afternoon session. However, the results of the first half who took the test in the morning cannot be combined with the results of the second half who took the test in the afternoon.

For larger scale surveys with survey personnel more than 20, more days will be required to conduct the test to appropriately and to correct specifications.

### Steps in carrying out the standardisation test {#sec-standardisation-test-steps}

1. The supervisor carefully performs the measurements on each child without allowing the teams to see the values. The supervisor records his/her measurements on the standardisation test form for the first round of measurements.

+----------+-------------+-------------+-----------+-----------------+
| Child ID | Weight (kg) | Height (cm) | MUAC (mm) | Oedema (yes/no) |
+==========+=============+=============+===========+=================+
| 01       |             |             |           |                 |
+----------+-------------+-------------+-----------+-----------------+
| 02       |             |             |           |                 |
+----------+-------------+-------------+-----------+-----------------+
| 03       |             |             |           |                 |
+----------+-------------+-------------+-----------+-----------------+
| 04       |             |             |           |                 |
+----------+-------------+-------------+-----------+-----------------+
| 05       |             |             |           |                 |
+----------+-------------+-------------+-----------+-----------------+
| 06       |             |             |           |                 |
+----------+-------------+-------------+-----------+-----------------+
| 07       |             |             |           |                 |
+----------+-------------+-------------+-----------+-----------------+
| 08       |             |             |           |                 |
+----------+-------------+-------------+-----------+-----------------+
| 09       |             |             |           |                 |
+----------+-------------+-------------+-----------+-----------------+
| 10       |             |             |           |                 |
+----------+-------------+-------------+-----------+-----------------+

2. Each team starts with a different child, and the first half of the team measures the child once and records the results in a standard form for the first measurement (as above). The current measurer should make sure that he/she is entering data in the row corresponding to the child ID of the child he/she is currently measuring.

3. When the first half of the team has done the measurements for the current child, they should move on to the next child. After the first half of all the teams has measured 10 children once, the first measurement round forms are handed in. The teams and the children then take a break. Appropriate incentives including food and drinks to snack on during the break should be provided to the mothers and children.

4. After the break, the first half of the team repeats the whole process and measures each child for the second time and records his/her measurements onto the standardisation test form for the second round of measurements. After the the first half of all the teams has measured 10 children twice, the second measurement round forms are handed in. The teams and the children then take a break for lunch (end of first half of the day/first half of the test). Appropriate lunch arrangements should be prepared for the mothers and children.

5. After the lunch break or on a new day altogether, the whole process is done all over again but this time, the second half of the teams will be performing the measurements. Ideally, the same set of mother and child pairs should be utilised for the second half day of testing. However, it may be that some of the mothers will be unable to come back to help. If for the second half day of testing the mother and child pairs are different from the first half day, then measurements made in the second half day cannot be mixed with the data from the first half day when reporting on the performance in the standardisation test of the survey personnel.
