An introduction to design engineering
An introduction to design engineering

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course

An introduction to design engineering

4.5 Visualising numbers

Histograms are used to plot quantitative data, with ranges of data grouped into intervals. For instance, Figure 15 shows a histogram of 200 people using height ranges of 20 mm, with heights measured to the nearest 1 mm. Notice that the values on the horizontal axis are continuous – the first bucket goes from 1600 mm to 1619 mm, the second from 1620 mm to 1639 mm, and so on. The vertical axis shows percentages. The area of each bar represents the percentage of people whose height falls in that range, and the sum of all the areas would equal 100%.

Described image
Figure 15 Histogram of heights (mm) of 200 people in 20 mm buckets

Bar charts can be used to group and count the frequency of anything, using categories that are not necessarily numerical. Figure 16 shows a bar chart representing a packet of sweets – sorting and counting the sweets according to flavour makes it possible to say something useful about how those flavours are distributed.

Described image
Figure 16 The distribution of sweet flavours in a single packet shown as a bar chart. Clearly the author’s favourite flavours appear least often!

In Figure 16 the values on the horizontal axis (x-axis) represent a category − flavour in this case − and the vertical axis (y-axis) states how many sweets fell into that category. The bars could have been drawn in any order, but ordering them by size as in this case is often most informative.

T192_1

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371