Today, lets talk about indexing, a technique used to compare changes in values over time.

What is indexing?
Lets say you want to compare prices of Gold & Coffee over last few years. Gold price in 2011 (oct) is $1,655 per ounce. And now (sept 2012) it is $1,744. Like wise, Silver price in 2011 is $32.06 and in 2012 it is $33.61. How do we compare such diverse numbers?
Enter indexing.
First we need to calculate price of Gold and Silver in 2012 assuming their starting price is 100. This can be done with simple arithmetic.
We will get this:

Now, we can easily compare the prices. Looking at the indexed prices, we can conclude that both Gold & Silver prices have gone up by similar percentage (~5%).
When to use Indexing?
There are many good reasons to use indexed values. Some of the common reasons are,
- To compare values which are vastly apart – ex: price movements of gold, silver & coffee
- To understand growth (or non growth). Subtract 100 from any indexed value to know how much it has grown (or shrunk) compared to base value.
- To understand change with respect to a bench mark – ex: performance of a company with respect to stock market index.
For more detailed discussion on indexation & its applications, refer to this article by Paresh.
Indexed Chart Example – Commodity prices in last 5 years
Lets say you are a savvy commodity investor and want to understand how the prices of gold, silver, bananas and coffee have changed since 2007. Now, each of them have a different range of values and comparing all of them in same chart can be very confusing.
Let us index the values to 100 and then compare.
Step 1: Arrange your data.
Lets assume we have our data like this:

Step 2: First indexed value is 100 for all items
Step 3: Calculate next indexed value using simple formula.
See this illustration to understand how to calculate the indexed values.

Step 4: Make a line chart
Select the indexed values and create a line chart. And you are done!
Step 5: Format the chart
This is where you can unleash your creativity. Add labels, legend, format axis etc. Here is a version I came up with.

Download Indexed Chart Example
Click here to download example workbook & play with it. Poke the formulas & chart options to understand this better.
Do you use Indexed charts?
I use indexing technique often to compare various metrics in my own business. I also use these type of charts in various dashboards & client reports.
What about you? Do you use indexation as a technique to compare values? What other techniques you rely on? Please share using comments.
More charting techniques:
- Show both average & distribution of data in your charts
- Use multiple charts to give users a choice of analysis
- Analyze competition with scatter plots
- How to chart when you have lots of small & few very large values?
- Use small multiples (panel charts) to to compare lots of things
- More charting examples & charting principles














23 Responses to “Learn Top 10 Excel Features”
What it looks like if excel without formula?? 🙂
It would be not excel it would just be fancy tables in which you could just use power point. (Chandoo) would Access be an alternative?
Awesome piece of work!!!
Great article.
Chandoo - my biggest interest in the article was the awesome word-graphic at the top - where did you go to get it done into a shape?
@Rich.. thank you. I used http://www.tagxedo.com/ to generate this word cloud. I took all the comments in the original post, pasted them in tagxedo website and set up the shape etc.
Awesome Chandoo.. You need always needs coffee to start up with. BTW , how did u created the Heart Shaped picture filled with High Repetitive text in it .. Please put it on your Next blog ...
Chandoo, good article. I’ve added a link to it from Connexion – our collection of the most useful and interesting spreadsheet-related articles from the web. See http://www.i-nth.com/resources/connexion
Hi,
Just one small question. Where the hell have been I in the past for not discovering this website sooner?
I've lost a job interview recently where even though I had the subject knowledge, I was not upto their mark in Excel.
Thank you for all the free tips, guidance and for creating this forum environment.
[PS: I've just been through the site for the 1st time, and have signed up for the newsletter. You can expect pretty stupid questions from me soon]
Hy Chandoo, you always inspire me with to explore something new in excel. This data structure table is only for excel 2007 or compatible to 2010. I recently installed latest excel version 2013 in my System and experience problems regarding operating according to previous one. I'm waiting your article relates to that excel version.
Thanks
Awesome article Mr. Chandoo and that is a awesome heart shaped pic you created. Great tips as well.
[...] Learn Top 10 Excel Features | Chandoo.org – Learn Microsoft Excel Online. [...]
Chandoo is awesome..
Thanks, i got better, And i always get 90.50 in my grade card but now i get 96.50 i improved because of the tutorials you gave, Thank You Very Much Chandoo Guy.
Hi chandoo, i am intersted in seeing the video or step by step done procedure of analysing the comments and presenting in the data percentage steps. I think this one would be first step in finding out how generally happens data calculation. Thank you.
As well i would like to know how to get that black shape art of your face which i see in chandoo. I am interested in making it for me.
Nice to see the features considered by Excel users to be most useful. It might be a good idea to also analyze StackOverflow Excel questions to see what keywords appear most often.
Here are my top 10 Excel Features (for advanced users):
http://www.analystcave.com/excel-10-top-excel-features/
Thanks a ton for this it totally helped with my homework ????
Very good effort
Thank you for this. Lots of learning in the links you've provided for this septuagenarian.
Pls send me new post
Dude, your humor ? ?
Loved your work.
Hello Sir,
I am Sanjeev Khakre and i from Indore City, India , I am your big follower and i have watch your videos and learnt a lots of excel trick or function and many more . thanks so much for all of your excellent support.
Your excel knowledge is real awesome.
Thanks
Sanjeev
Your work is excellent but pls willing to know more details about the features of microsoft excel
Chandoo Would Access be a better alternative than VB?