Page 104 - MAT KS3 Y8 Cambridge CheckPoint

10 Processing and presenting data

The internet is full of facts and figures. Data is everywhere. People Key words
in almost every profession gather data all the time, so that they can
use it to obtain information. Make sure you learn and
understand these key words:
How do they obtain information from data?
statistics
Many of them calculate statistics from the data. A statistic is any mode
number that is obtained from a set of data.
median
You should already be familiar with some simple statistics. mean
r There are three types of average: the mode, the median and the average
mean. Each of these uses one number to represent a set of data. range
r You should also know about the range. It describes how spread frequency
out the data is. class
modal class
This set of data is the ages of a group of 20 people.

12 11 15 12 13 11 13 14 12 14
11 14 11 14 12 14 14 11 14 14

You could show the ages more neatly in a frequency table.

Age 11 12 13 14 15
Frequency 5 4 2 8 1

In this example, the mode is 14 years, the median is 13, the mean is 12.8 and the range is 4 years.
The average age is about 13 or 14 years, depending on which average you use.

Why are there three different averages?
Different averages have different uses.
The mean is often used when you talk about average prices, costs, production, masses or heights.
The median is often used when you talk about income, wealth or qualities such as intelligence.
The mode is often used when you look at clothing sizes, weather forecasting and some applications
in biology and business.

In this unit, you will learn more about discrete and continuous data, and find out how to calculate
statistical information from both types.

102 10 Processing and presenting data