Scottish Health Survey 2015 - volume 2: technical report

4 Weight Measurement

4.1 Introduction

Similar to the height measurement, the weight measurement is an indicator of and can predict the nutritional status and health of a population. When used in conjunction with the height measurement it can be used to derive the Body Mass Index, a statistical measure used to determine if an individual's weight falls within a healthy range.

4.2 Exclusion criteria

Participants are excluded from this measurement if they are:

• Pregnant
• If the woman wishes to be weighed, you can but do not enter the results into the computer.
• Too frail or unable to stand upright
• If you are concerned that being on the scales may cause them to be too unsteady on their feet then do not weigh them. Alternatively you can place the scales next to something that they can steady themselves on.
• Over 130kg (20 ½ stone) in weight as the maximum weight registering accurately on the scales is 130kg. If you think that the Participant exceeds this limit then code it appropriately in CAPI and follow the prompts. Do not attempt to weigh them.

4.3 Equipment

There are different sets of scales in circulation on NatCen projects. You will be provided with either:

Tanita THD-305 scales

The weight is displayed in a window on the scales. The scales are switched on by pressing the button on the bottom right hand corner of the scales. They are battery operated and require four 1.5v AA batteries, which should be sent with the scales. They may be packed separately or one of the batteries may be turned around, to prevent the batteries from going flat, as there is no on/off switch. Ensure that you have spare batteries, just in case you need them.

Seca 877 scales

The weight is displayed in a window on the scales. The scales are switched on by briefly covering the solar cell (for no more than one second). The solar cell is on the right hand side of the weight display panel. NB You may experience difficulties switching the scales on if there is insufficient light for the solar cell. Make sure that the room is well lit. The scales have a fixed battery which cannot be removed.

Please check which scales you have been provided with and make sure that you are familiar with how they operate.

You will also need a pack of Milton antibacterial wipes.

4.3.1 Calibrating the scales

The scales will need to be sent to Brentwood at regular intervals to be recalibrated to ensure that they provide accurate measurements. On each set of scales there is a label with a date that they need to be recalibrated by, ensure that they have been sent to Brentwood by this date.

4.3.2 Technical faults

Please refer to Table 1 when experiencing technical difficulties with the scales.

Table 1 Troubleshooting for the scales

Fault	Action
Tanita THD 305 scales
No row of 8s when turned on or will not turn on	Replace batteries If not solved, report to manager/Brentwood
Inconsistent readings	Make sure on hard flooring Ensure 0.0 on display when Participant steps on scales Replace batteries If not solved, report to manager/Brentwood
Seca 870 scales
No '1888' when turned on or will not turn on	Insufficient light to operate solar cell If not solved, report to manager/Brentwood
Inconsistent readings	Make sure on hard flooring Ensure 0.0 on display when Participant steps on scales Insufficient light to operate solar cell If not solved, report to manager/Brentwood

4.4 Procedure for adults

1. Weigh the Participant on a hard and even surface if possible. Carpets may affect measurements.

2. Ask the Participant to remove shoes, heavy outer garments such as jackets and cardigans, heavy jewellery, and to empty their pockets of all items.

3. Switch on the scales and wait for 888.8 (for the Tanita scales) or 1888 (for the Seca scales) to be momentarily displayed in the window. Do not attempt to weigh anyone at this point.

4. When the display reads 0.0, ask the Participant to stand with their feet together in the centre and their heels against the back edge of the scales. Their arms should be hanging loosely at their sides and their head should be facing forward. Having the Participant stand in this position means that the most accurate weight measurement can be obtained. Ensure that they keep looking ahead - it may be tempting for the Participant to look down at their weight reading. Ask them not to do this and assure them that you will tell them their weight afterwards if they want to know.

5. The scales will need to stabilise. The weight reading will flash on and off when it has stabilised. If the Participant moves excessively while the scales are stabilising you may get a false reading. If you think this is the case reweigh the Participant.

The scales are calibrated in kilograms and 100 gram units (0.1 kg). Record the reading in CAPI before the Participant steps off the scales.

7. If the Participant wishes, record the reading on their measurement record card.

8. The scales should switch off automatically a few seconds after the Participant steps off them.

9. Before packing the scales away ensure the footplate is wiped again to reduce potential cross infection between households.

4.5 Procedure for children

1. You must get the co-operation of an adult household member. This will help the child to relax and children, especially small children are much more likely to be co-operative themselves if an adult known to them is involved in the procedure.

2. Children who wear nappies should be dry. If the nappy is wet, please ask the parent to change it for a dry one and explain that the wetness of the nappy will affect the weight measurement.

3. Weigh the child, following the same procedure for adults. Encourage the child to 'Be as still as a statue' for an accurate reading. If you think that the results are inaccurate, code this in CAPI.

For very young children who are unable to stand unaided or small children who find this difficult follow the procedure below you will need to ask for the assistance of an adult as the following procedure requires you to measure the adult and then the adult holding the child:

1. Explain to the adult what you are going to do and the reasons why.

2. Code in CAPI the procedure used to measure the weight of the child.

3. Weigh the adult as normal following the protocol as set out above. Enter this weight into CAPI.

4. Weigh the adult and child together and enter this into CAPI . CAPI will calculate the difference between the two weights to get the child's weight.

5. If the Participant wishes record this reading on their measurement record card.

6. Before packing the scales away ensure the footplate is wiped again to reduce potential cross infection between households.