#Z score definition plus

Moderate acute protein-energy malnutrition is defined as having a weight-for-height z-score of -3.0 to less than -2.0. The table below is more like a real anthropometry table because it has the standard deviation, the average minus two standard deviations, and the average minus three standard deviations for this group of children in the WHO standard population.Ībsence of acute protein-energy malnutrition, or normal nutritional status, is defined as having a weight-for-height z-score of -2.0 or greater. This allows us to quickly tell where our individual child is relative to these two points without having to calculate an exact z-score. This table also shows the value for the average minus two and minus three standard deviations. We get the average and standard deviation of the reference population from the anthropometry tables. We can calculate the girl's exact z-score by using the formula: Standard deviations can also be called z-score, hence the terminology of -2.0 z-scores (two standard deviations below the average) and -3.0 z-scores (three standard deviations below the average). We can see that our girl is slightly above the average minus 3 standard deviations and below the average minus 2 standard deviations. At the bottom of the graph is shown the average minus two and the average minus three standard deviations, calculated from the average weight and standard deviation of all girls who are 80 cm tall, as given in the anthropometry tables. It also shows where on this graph our individual 80 cm girl is located. The graph below shows the distribution of weights for all 80 cm girls in the reference population, as shown before.

#Z score definition plus

95% of the children in the group have a weight between 8.0 kg and 12.0 kg (the average plus and minus two standard deviations).

The area between the mean plus two standard deviations and the mean minus two standard deviations represents 95% of the measurements.įor example, is the average weight for a group of children is 10.0 kg and the standard deviation is 1.0 kg, then 67% of children in this group have a weight between 9.0 kg and 11.0 kg (the average plus and minus the standard deviation). If we add one standard deviation to the average and subtract one standard deviation from the average, 67% of all the measurements lie between these two numbers, as shown on the graph below. The number after the 'SD' is the standard deviation. For example, you have probably seen measurements given as something like16.3 (SD = 2.3). The standard deviation is calculated from the actual collection of measurements. The peak of the curve is the average of all the measurements. The people in the population on the right are much more similar to each other their weights do not show such a wide range. There are some very light people and some very heavy people. If, for example, the measurement plotted on the graphs below is weight, the population in the left graph has a wide range of weights. Other data are not very dispersed, as shown on the right graph, meaning that the values for individuals are quite similar to each other. Some data are quite dispersed, as shown on the left graph, where the values for individuals may be quite different from each other. Some background is necessary before discussing anthropometric z-scores.Ī z-score, or standard deviation, is a measure of the dispersion of data. This is a bit more complex but has certain advantages over percent of median and is widely used to present survey results. The second way to express the distance between an individual child's weight and the average weight of comparable children in the reference population is by z-score.

Formulating conclusions and recommendations.

Micronutrients - Biochemical indicators.

Nutrition - Indicators and their measurement.

Nutrition - Introduction and background.

Mortality - Indicators and their measurement.

Surveys - Resources required for surveys.

Surveys - Sampling error, bias, accuracy, precision, & sample size.

Surveys - Description of sampling methods.