A common type of data presentation is in the form of charts – in particular, bar charts. Learning about bar chart and how they present information can help you make better inferences.

What are bar charts?

Bar charts or graphs, like tables, present values based on certain categories. Unlike tables that show this in a column or row, bar charts generally use axes (X and Y and sometimes 2 x-axes – in other charts the horizontal axis is called the x-axis but in bar charts, the horizontal line is called the y-axis) and display values in a visual format to make it easier to understand.

They come in various formats but can be distinguished by the presence of “bars”. Let’s look at three in particular and discuss them, paying attention to (see video for full discussion):

• Information the chart is conveying (orientate yourself)
• Big picture -> Get into the detail.
• Any insights? Is there anything that has likely been excluded?

Source: Data.gov.au is licensed with CC BY 4.0.

Source: Data.gov.au is licensed with CC BY 4.0.

Source: Data.gov.au is licensed with CC BY 4.0.

How to answer questions involving data in bar charts

Interpreting data is very much based on the individual graph at hand. But there are general rules that you can follow:

1. Know the requirement.
2. Orientate yourself with the background – e.g., title, units, axes, legend/key.
3. Questions may ask you to locate data points or they may ask you to find ‘categories’ for certain data points and this will determine whether you’re working top-down or bottom-to-top.
4. If working top-down, use the axes to navigate and ‘zoom in’ on individual data values.
   
5. If working bottom-to-top, look at the bar directly for size – longer bars indicate a larger value while shorter bars represent lower values. Once done, identify their categories from the axes.
6. Make inferences where appropriate.

Let’s see it in action now with a worked example.

Example Question/s

Watch video for explanation of the following question/s:

Profit is when the sales price of a product exceeds the cost of making or acquiring the item for sale. For example, profit is $100 when it costs $10 to buy materials and create a necklace which you sell for $110. If it instead costs you $110 to buy materials and create the same necklace and you sell the necklace for $10, then you have made a loss of $100 or the profitability of the necklace is -$100.

The below chart shows the profitability of two types of cake sold in a cake shop. Which one of the following statements is true?

Modified from source: Data.gov.au is licensed with CC BY 4.0.

A. No butter cakes – with flour were sold in 2018.
B. There was a loss in any one cake type each year, except for 2021.
C. Both cakes turned a profit from 2020 onwards.
D. More butter cake – flourless was sold than butter cake – with flour from 2017 through to 2021.

Key Rules to remember

• Use the general rules in working with data – requirement, orientate, ‘zoom in’.
• Bar charts ‘tally’ values and there are different variations – stacked, horizontal, vertical etc…
• Use visual cues – a longer bar means a higher value while a shorter bar means a lower value.
• Look at where the bars intersect – where is 0 or the base level?
• Stacked bars show an overall total and individual amounts and avoid confusing the two.

Practice time!

Now, it's your turn to practice.

Here’s a thought experiment #13.

Remember, there is no formal answer and this experiment is provided to help stimulate your creativity and critical thinking (a ‘thought experiment’ is provided at the end of every checkpoint except checkpoint 18).

Thought experiment 13:

If people had the ability to fly naturally, how would this change the world – would it make the world a better place, the same or an inferior place?

Take your time to work through this thought experiment as it is not assessed and provided to help develop your deeper thinking skills. Think about various components of the question. What questions will you ask yourself and how do you answer your questions?

Now, let’s turn to the checkpoint questions.

Click on the button below and start your practice questions. We recommend doing untimed mode first, and then, when you're ready, do timed mode.

Every question has two solutions videos after you complete the question. The first is a quick 60 second video that shows you how our expert answers the question quickly. The second video is a more in-depth 5-steps or less explainer video that shows you the steps to take to answer the question. It's really important that you review the second video because that's where you'll learn additional tips and tricks.

Once you're done with the practice questions, move on to the next checkpoint.

Now, let’s get started on your practice questions.

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