Lets say you have a large list of numbers, and you want to calculate the average of every nth value. Not the average of all numbers, but just every nth number.
That is what we will learn in next few minutes.
Few assumptions
Before we jump in to any formulas, first lets assume that all your data is in a table, conveniently named as tbl. Lets say this table has below structure.
Also, the value of n is a named cell N.
Average of every nth value
Approach 1: Using helper columns
If you have no allergies towards nuts, dairy or helper columns, then this approach is easiest.
We just add an extra column to our tbl , called as helper.
In the helper column, write this formula.
=MOD([@ID], N)=0
This will fill the helper column with TRUE & FALSE values, TRUE for all nth values, FALSE for everything else. See aside.
Once we have the helper column, calculating average of every nth value is easy as eating every slice of a cake.
We use AVERAGEIF to do this.
=AVERAGEIF(tbl[Value],tbl[Helper],TRUE)
Approach 2: Not using helper columns
Now things get interesting. Lets say you want to calculate average, but not use any helper columns.
First the formula:
=AVERAGE(IF(MOD(tbl[ID], N)=0,tbl[Value]))
Array entered.
Lets understand how it works:
We want the average of every nth item of tbl[Value] column.
In other words, we want average of every item of tbl[Value] column, whose corresponding tbl[ID] value is perfectly divisible by n.
How do we know when a value is perfectly divisible by another?
Don’t worry. You don’t have to do the long division on paper now. Instead we use Excel’s MOD function.
When a value is perfectly divisible by another, the reminder is zero.
So, MOD(value1, value2) = 0 means, value2 divides value1 perfectly.
That means…
We want the average of tbl[Value] when MOD(tbl[ID], N) = 0
Lets write that in Excel formula lingo.
=AVERAGE( IF(MOD(tbl[ID], N) = 0, tbl[Value]) )
This formula results in a bunch of values and FALSEs. Assuming N=3, this is what we get (for sample data):
=AVERAGE({FALSE;FALSE;15;FALSE;FALSE;18;FALSE;FALSE;18;FALSE;FALSE;15;FALSE;FALSE;14; …})
Since AVERAGE formula ignores any logical values, it will calculate the average of {15, 18, 18, 15, 14 … } and returns the answer you are expecting.
As this formula is processing arrays instead of single values, you need to array enter it (CTRL+SHIFT+Enter after typing the formula).
Bonus scenario: Average of FEBRUARY values only!
Here is a bonus scenario. Lets say you want to calculate the average sales of FEB alone… Then you can use AVERAGEIF (or AVERAGEIFS, if you want to have multiple conditions).
=AVERAGEIF(tbl[value], tbl[month], “FEB”)
Download example workbook:
Click here to download the example workbook. It contains all the techniques explained in this post. Play with the data & formulas to understand better.
Time for some challenges…
If you think averaging every nth value is not mean enough, try below challenges. Post your answers using comments.
- Write a formula to calculate average of every nth value, starting at row number ‘t’.
- Write a formula to calculate average of every nth value, assuming your table has only value column (no ID column).
Go ahead. Show off your formula skills. Post your answers in comments section.
Improving your Excel batting average
Calculating averages predates slice bread. Folklore says that when first neanderthal figured out how to express numbers and carved 2 of them on a cave wall, his manager walked by and asked “What is the average of these two? Eh?” and thumped her chest.
Although caves & wall carvings are replaced by cubicles & spreadsheets, we are still calculating averages, almost 2.9 million of them per hour.
So it pays to learn a few tricks about Excel Average formulas. Check out below to improve your average:
- Calculating Moving Average, Weighted Average
- Average of top 5 values
- Show averages & distribution in your charts
- Using SUMIFS formula (same tricks apply to AVERAGEIF, AVERAGEIFS too)
If your boss is the kind who thumps her chest and mocks you for your poor Excel skills, don’t cave in. Fight back. Enroll in Excel School and show that you can evolve.
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?