Module 1: Summarising data

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Median

The weights recorded for five new babies at a hospital on one day were:
3.2 kg, 3.6 kg, 4.2 kg, 2.8 kg and 3.4 kg. The list of weights for the five
babies were resorted from smallest to largest. The sorted list was: 2.8 kg,
3.2 kg, 3.4 kg, 3.6 kg, 4.2 kg.

The sorted list of baby weights show that the baby with the middle value
for weight equalled 3.4 kg at birth. The middle value in the sorted list is
called the median value.

The next day eight more babies were born. The weights for the new babies
were: 2.9 kg, 4.0 kg, 3.4 kg, 3.6 kg, 3.7 kg, 3.0 kg, 4.2 kg, 3.3 kg. The
list of weights for the eight babies were resorted from smallest to
largest. The sorted list was: 2.9 kg, 3.0 kg, 3.3 kg, 3.4 kg, 3.6 kg, 3.7
kg, 4.0 kg, 4.2 kg. The sorted list of baby weights show that the babies
with the middle values of the group were born with weights of 3.4 kg and
3.6 kg.

When there is an even number of values then the median is calculated by
taking the average of the two middle values. For this example, with the
weights for eight babies, the median weight equalled 3.5 kg.

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