Note: this was prepared for my ECON 3403 students, and is a list of all of the mistakes I commonly see in student charts. Please add your suggestions for things to add to this list in the comments - or steal, modify, and use for your own purposes! Good Chart Check List: Is my chart self-explanatory? Does it specify Who: The population the chart shows (e.g. eligible voters, Facebooks users, people over the age of 12, Canadian citizens, etc) Where: The geographic area the chart applies to (Ottawa, Canada, G7, G20, OECD) When the data was collected The data source (e.g. Statistics Canada Table 12-345-67, World Bank). Optional: give name of survey or statistical programme data came from. Am I using an appropriate chart type? Line chart to show time trends (typically 4+ observations –
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Note: this was prepared for my ECON 3403 students, and is a list of all of the mistakes I commonly see in student charts. Please add your suggestions for things to add to this list in the comments - or steal, modify, and use for your own purposes!
Good Chart Check List:
Is my chart self-explanatory? Does it specify
- Who: The population the chart shows (e.g. eligible voters, Facebooks users, people over the age of 12, Canadian citizens, etc)
- Where: The geographic area the chart applies to (Ottawa, Canada, G7, G20, OECD)
- When the data was collected
- The data source (e.g. Statistics Canada Table 12-345-67, World Bank). Optional: give name of survey or statistical programme data came from.
Am I using an appropriate chart type?
- Line chart to show time trends (typically 4+ observations – for just two years of data use a bar chart).
- Bar chart to compare groups of things, e.g. countries, age groups, genders, occupations, industries, provinces
- Pie charts are rarely the appropriate chart type. Use pie charts when your only concern is distribution; you only want to know how each group’s share compares to other group’s shares. If you must use a pie chart, consider using the “doughnut” option.
Are my axes clearly labelled? Is it clear
- What each axis represents Exceptions:
- do not have to label a “year” axis, it is usually obvious that 2005, 2010, 2015, 2020 etc are years.
- If the chart title makes it clear what the graph shows, don’t have to label the axis as well.
- What units I am using (miles, km, tonnes, millions of tonnes, Canadian dollars, 2020 (constant) dollars, nominal (not inflation adjusted) dollars, etc)
Have I put my data into perspective?
- For data showing trends over time: are dollar amounts adjusted for inflation?
- For comparisons across provinces or across countries: am I showing numbers as a percentage of the population, to adjust for population size?
- For data focussing on a particular population subgroup: have I included data for other groups to put the numbers into perspective? E.g. for a chart showing trends in 12-15 year old’s mental health, consider including mental health trends for the entire population to put the numbers into perspective. For a chart showing poverty rates for elderly, include poverty rates for the non-elderly for comparison purposes.
- For data showing trends over time: have I tried the “year 1=100” approach – i.e. divide by the year 1 value*100?
Am I being honest?
- Does my vertical (y) axis start at zero?
- Exception: sometimes, if you’re trying to highlight trends, it’s o.k. to have a line chart that doesn’t start at zero. But be very careful! For a bar chart, the vertical (y) axis must ALWAYS start at zero!
- Am I selecting my starting year carefully to show the results I want to show? (e.g. I am I showing stock market growth starting at 2009, when the market was at very low levels, instead of at 2007?).
- Am I distorting my results using fancy graphics, especially 3-dimensional shapes?
- Are the numbers on my chart accurate?
- Have I created a combo-chart, and manipulated my axes so that my series look closely related, when they really aren’t?
Is my chart accessible?
- Can someone who is colour-blind read my chart?
- Can someone who has trouble reading small print read my chart?
- Flip a bar chart on its side (so the bars are horizontal, not vertical). That creates room for big-enough-to-read labels!
- Consider putting legend labels on the chart itself, rather than to the side (requires advanced Excel skills)
- Does my chart contain any unnecessary information or other clutter?
- Avoid cluttering up a graph with too many years worth of data. Zoom in on one year and compare population groups (e.g. age, sex, industry, occupation). Alternatively, download 5+ years of data and graph a time trend (challenge: can you explain the trend?). Statistics Canada data tables often include 3 years of data by default. However a good graph rarely includes just three years of data (exception: the years 2019, 2020, 2021).
- Only report 2 or 3 digits worth of data – e.g. report data as 1.2 million rather than 1,234,567.
- Cut any unnecessary lines, words or graphics
- Am I using the right words to describe wages and incomes?
- Wage rate=$ earned per hour worked
- Wages=total amount earned. Also known as earnings
- Income=earnings +other sources of income.
- For income data, try to be as precise as possible.
- Is the data pre-tax income or after-tax? If after-tax income, does it include benefits like Canada Child Benefit?
- Individual income or family income or household income? If family or household income, whose income is counted? (e.g. if a 25 year old is living with a parent, whose income is included in the 25 year old’s “family income”?) Check to see if the income is “census family income” or “economic family income”.