Bar chart or Line? Scatter plot or box plot? These are the questions we ask ourselves when we set out to make a chart. In this article let me tell you how to pick a chart type so you can make best charts for every situation.
Why is it important to pick right chart?
Because right charts lead to right decisions. We use charts to tell stories, evaluate alternatives, understand trends or find-out if everything is normal. So, an incorrect charting choice can lead to poor judgment of the messages where as a correct chart can lead to right and faster decisions.
How to pick a chart type:
Chart making process can be divided in to 4 steps
- Find-out what you want to say?
- (Re)arrange the data
- Prepare the chart
- Format the chart
1. What is the purpose of this chart?
This is the first and most important step in chart preparation. You must ask yourself, “what is the purpose of this chart?”. Once we know the clear reason why the chart should exist, we will naturally be able to select the correct chart type for that reason.
But I realize that finding the reason itself can be a bit tedious. So I have listed down 6 common reasons that we often have to make a chart:
- to Compare
- to show the Distribution
- to explain Parts of the Whole
- to tell the Trend over time
- to findout the Deviations
- to understand the Relationship
Let us understand these reasons along with the type of charts that go well with these.
1. To Compare:
What it means? You want to compare one set of value(s) with another.
Examples:
- Performance of Product A vs. Product B in 5 regions
- Interview performance of various candidates
Charts that can be used for this reason:
- Bar Charts,
- Column Charts
- Scatter Plots
- Pie Charts
- Line Charts
- Data Tables
2. To Show the Distribution
What it means? You want to show the distribution of a set of values (to understand the outliers, normal ranges etc.)
Examples:
- Distribution of Call waiting times in a call center
- Distribution of bugs found in 10 week software testing phase
Charts that can be used to show distribution:
- Column Charts
- Scatter Plots
- Line charts
- Box Plots
3. Parts of Whole
What it means? You want to show how various parts comprise the whole
Examples:
- Individual product sales as a percentage of whole revenue
- Browser types of customers visiting our website
Charts that can be used to show Parts of Whole:
- Column Charts
- Bar Charts
- Pie Charts
- Data Table
4. Trend over time
What it means? You want to understand the trend over time of some variable(s).
Examples:
- Customer footfalls on the last 365 days
- Share price of MSFT in the last 100 trading sessions
Charts that can be used to show Trend Over Time:
- Column Charts
- Line Charts
- Data Table
5. Deviations
What it means? You want to see which values deviate from the norm.
Examples:
- Failures (or bugs) in the context of Quality Control
- Sales in Various Stores
Charts that can be used to show Deviations:
- Column Charts
- Bar Charts
- Line Charts
- Data Table
6. Relationship
What it means? You want to establish (or show) relationship between 2 (or more) variables
Examples:
- Relationship between Search Phrases and Product Purchases in your website
- Relationship between in-store sales and holidays
Charts that can be used to show Relationship:
- Scatter Plot
- Line Chart
- Data Table
How to pick a chart type when you have more than one reason for the chart?
Simple, use common sense. If I were you, I would either cut down the messages to one or make 2 charts (each conveying one message). If that is not possible, I would consider using dynamic charts or combination charts.
2. (Re)arranging the Data
Even when we know the message and corresponding chart, sometimes, our data may not support us. We then have to rearrange the data. Using excel formulas, pivot tables, tables and data cleaning tools we can easily massage the data.
Once we have the data in required format, we proceed to step 3.
3. Prepare the chart
Since you have already picked the chart type in Step 1, this is very straight forward. Most of the regular charts are available in MS Excel as default charts. You can insert them with few clicks.
But for some special chart types, you may have to prepare the chart by helper series, formatting etc.
4. Format the chart
While most formatting is done as per individual taste, there are some ground rules that apply on almost all charts. Here they are,
- No non-zero axis scale on bar charts [reasons and discussions]
- Make subtle grid-lines (or remove them) [how to remove grid lines]
- Add labels to important points [labeling techniques]
- Add descriptive, bold titles
- Position axis, scales at the right places (for eg. y-axis to the right on a large time series chart)
- Use simple, easy colors
A final word:
The ideas in this post are meant to be guide lines, not final words in the world of visualization. While these rules can help you make a good chart, a great chart take so much more. Knowledge of your data, Passion for what you do and Genuine focus on your audience’ needs can make your chart truly outstanding. All the best.
References:
Communicating Numbers – White Paper by Stephen Few [PDF]
Resources & Further Help:
- Chart chooser – Juice Analytics
- Data vis 101 – How to choose a chart – Hubspot
- Selecting right char type – KD Nuggets
- Charting Principles
- Charting Tutorials from Peltier Tech
- More articles from Stephen Few
- Charting Wisdom from Jorge Camoes
What is the process you use for Chart Selection?
I would love to know the process you use when selecting a chart type. Please share using comments.
13 Responses to “Gantt Box Chart Tutorial & Template – Download and Try today”
Hi Chandoo
As one of your students I have followed your detailed example through with great success. However, Excel is acting in an unexpected way and I wonder if you could take a look?
http://cid-95d070c79aef808e.office.live.com/self.aspx/.Public/Gantt%20Box%20Chart.xlsm
On my version, I have to type 40239 (Which equates to 2 Mar 2010) to get the chart to display 31 May 2010 (which should be 40329)!!??
Have I done something wrong or is Excel acting up?
Thx
Oli
PS Your example file in 2007 displays correctly.
Hi,
I like this idea a lot, but I agree the name is a little drab.
As an American I may just be seeing things, but to me the combination of lines and bars on your chart looks like a bunch of cricket bats.
Maybe you could work that into a catchier name. 🙂
Cheers!
Here is some code I use to keep the axis synched.
It may be useful to some of your readers
It is based on a comment I saw on Daily Dose of Excel.
Function SynchGanttAxis(Cname, lower, upper)
'Sets the X min and X max for Category axis
Application.Volatile
On Error Resume Next
'
'Top Horizontal Axis
With ActiveSheet.Shapes(Cname).Chart.Axes(xlCategory, 1)
.MinimumScale = lower
.MaximumScale = upper
End With
'Bottom Horizontal Axis
With ActiveSheet.Shapes(Cname).Chart.Axes(xlValue, 2)
.MinimumScale = lower
.MaximumScale = upper
End With
End Function
Function SynchVerticalAxis(Cname, lower, upper)
Application.Volatile
On Error Resume Next
' Excel 2007 only
'Right hand vertical axis
With ActiveSheet.Shapes(Cname).Chart.Axes(xlValue, 1)
.MinimumScale = 0
.MaximumScale = upper
End With
End Function
@Oli.. Can you check your file again.. I see 40329...
@Dave: Even I saw things.. the bars actually looked like lollipops. How about calling this lollipop chart - now that would be yummy and goes along the tradition of naming charts after eatables (bar, pie, donut...)
@Bob: Superb stuff... thanks for sharing 🙂
Hi Chandoo
This looks really good and I think it can also be applied to show project phases / milestones.
Question: Thinking further could this be amended to display a project lifecycle (Idea through to Implementation say 7 phases) on one bar / row? Just imagine 20 projects within a programme all on one chart one bar each showing their respective lifecycle stages i.e. on one page.
Idea: As the Gantt Box Chart this is quite intensive to set up re formatting etc how about the added extra of once you have completed this to "Save as template" i.e. saves the formatting and layout of the chart as a template so you can apply to future charts. Simple to do and will save the time formatting etc again and again and again.
Therefore tip: Click on your chart demo and then click on Save As template icon (2007) - edit file name and click on save. Ready to use / apply via Templates in Change Chart Type window.
Thanks and be very interested if the lifecycle question can be resolved
Mike
How embarrassing.
I was obviously suffering from numerical dyslexia. I was one of those days.
@Mike H: You can easily make this chart to work like a generic project lifecycle plan chart. All you have to do is,
1. in a separate sheet define the steps of lifecycle and various dates in a table (with 5 columns for each of the projects you have).
2. now use a control cell to input the project name you want to show in the chart
3. based on the input, use OFFSET Formulas to get the correct data
4. Rest is same as the tutorial above
For more info on the dynamic charting visit http://chandoo.org/wp/tag/dynamic-charts/ and http://chandoo.org/wp?s=OFFSET
Your solution is really smart but in the en Excel isn't meant to do stuff like this. I, as a former PM, always thought is was frustrating that you had to do stuff like this for something simple like a Gantt chart. So I built Tom's Planner. And would like to plug it here. I think it really solves the problem you are trying to solve in the most efficient way. Check out http://www.tomsplanner.com for a free account or play around with the demo.
Hi there,
Chandoo - this is really a very nice and helpfull chart - I adopted it, so I can report a forecast or the delay of a certain task (coming from my role as an auditor for projects).
One topic I´m currently struggeling with: I do have a project lasting for lets say 12 month. For a management reporting, I want to have kind of snapshot, lets say one month back and 2 month in the future. I tried with the offset formula, but failed. Any idea?
Thx
Lopi
[...] Ein viel geliebter Klassiker ist die Erstellung von GANTT-Diagrammen mit Excel. Wir hatten das Thema wiederholt schon hier. Chandoo.org hat sich mal wieder mit einer neuen Variante hervorgetan: Das GANTT-Box-Chart. [...]
[...] [...]
Hi Chandoo - fantastic xls. One thing I can't figure out how to do is adjust the alignment of the vertical axis. I would like to left align so that I could indent to represent sub tasks. Can that be done? Or is there a better way?
I've been trying to work out if there's a way to show weekends on the graph. The closest thing I've got is to add them on a secondary axis, but then I haven't been able to keep both axis lined up together! Any ideas?
Following on from this - is it possible to show things like holidays?