SOP for Height and Weight measurements

Height should be recorded to the nearest complete 1 cm using the same stadiometer for all measurements.

1. Ask the participant to remove shoes, hat and bulky clothing such as coats and sweaters. You may need to ask some participants to adjust hairstyles or remove hair accessories that may interfere with measurement.
2. The participant should stand erect, with shoulders level, hands at sides, knees or thighs together and with weight evenly distributed on both feet. Feet should be flat on the floor with both heels comfortably together and touching the base of the vertical board or wall. When possible, all four contact points (the head, back, buttocks, and heels) should touch the vertical surface while the participant also maintains a natural stance. Some people may not be able to keep a natural stance if all four contact points were touching the vertical surface. For these participants, at a minimum, two contact points — the head and buttocks, or the buttocks and heels — should always touch the vertical surface.
3. Ask the participant to move their head or position the participant’s head by placing a hand on the chin and moving it into the Frankfort Plane. The Frankfort Plane is an imaginary line from the lower margin of the eye socket to the notch above the tragus of the ear. When aligned correctly, the Frankfort Plane is parallel to the horizontal headpiece and perpendicular to the vertical back piece of the stadiometer. This is best viewed and aligned when the investigator is directly to the side and at eye level with the participant.
4. Lower the horizontal headpiece until it firmly touches the crown of the head and is at a right angle with the measurement surface. Ask the subject to inhale deeply and check contact points to ensure that the lower body stays in the proper position and heels remain flat. Reposition the head board if necessary. Read the height to the nearest complete 1 cm. If the reading is to xxx.5cm always round down to the nearest complete 1cm. Do not round up. Record results immediately.

Weight should be measured to the nearest to 1 kg.

A digital scale or balance beam is recommended for the measurement of weight. The same scale should be used for all measurements. Ideally the scales should be calibrated at least annually by a local procedure. Whatever kind of scale is to be used, checks should be made and any necessary adjustments to ensure that the scale reads ‘0’ before each measurement. The scales should be placed on a flat, firm floor surface.

The participant should ideally be wearing normal lightweight indoor clothing. Ask them to remove shoes, coats, jacket and heavy objects from pockets such as telephones or keys. Ask the participant to step onto the centre of the scale platform and stand up straight with arms relaxed at their sides and looking straight forward.

Staff involved in the recruitment should be properly trained to conduct height and weight measurements based on the on the method described here. Training should begin with a discussion and demonstration of the methods. The ‘trainee’ should then be asked to perform duplicate measurements on three different individuals. Height and weight should be recorded for each individual once and then the process repeated for a second recording of measurement. The ‘trainer’ should also undertake the same measurements on one occasion. Adequate training is achieved where the trainee’s repeat measurements are within 1kg and 1cm of each other and the mean of the repeat measurements are within 1kg and 1cm of the trainer’s measurements. If reproducibility is not met, repeat the training process -beginning with a review of the methods, until the required standards are achieved.