Dummy Data – How to use the Random Functions
Using collected or known data is the best when developing Excel models, but from time to time this may not be available when you are developing your model.
This post will look at some options for setting up Dummy Data using Excels Random functions.
Variability
Real data displays a range of variability, but this variability is generally within ranges or distributions of ranges of results.
All fields type can contain variability
ie: Country, State Names and Zip/Postal Codes, Maybe large lists but are fixed
Peoples Names, Maybe a large lists but are fixed by local rules
Ages, generally less than 80, never less than 0
Dates: Rarely before 1990 or 1900 in rare cases
Lists: are fixed
Numbers: generally random or conforming to a fixed distribution or known trend
Numbers: may include integers, decimals, negatives, extremely large numbers or all combinations
In generating random lists you will need to choose if you want random data, random data within constraints or random with a distribution. The choice is really yours and should in part be based on what the data is being used for and how accurately it needs to reflect reality.
Techniques
The techniques described below are all shown with a worked example in the attached Examples File or the Excel 2003 Example
Each example is annotated below like (Example 4.). ie: Refer to Example 4 in the above example files.
Dates
Setting up Random Dates is a simple process using the Date function.
=Randbetween(StartDate,EndDate)
Dates in a Range of Years
=Randbetween(Date(2000,1,1),Date(2011,12,31))
Will give a list of Random dates between 1 Jan 2000 and 31 Dec 2011 (Example 1.)
(Thanx Mike W)
Dates in a Month
=Date(2010, 6, Randbetween(1,30)
Will give a list of Random dates between 1 June 2010 and 30 June 2010 (Example 2.)
Don’t worry that the above formula (Example 1) can actually produce a 31 Feb 2005, the Date function will happily convert that to 3 March 2005 (Example 3.)
Dates within a Date Distribution
=DATE(2011,7,NORMINV(RAND(), 0,60))
Will give a list of Random dates between approximately 1 Jan 2010 and 31 Dec 2010, with a mean of July 1 and standard deviation of 2 Months (60days) (Example 4.)
Where NORMINV(RAND(), 0,60) will return values between -180 and +180, 99.7% of the time
Text Fields
Dependant on how many items in the list you require there are 3 techniques available
Choose
For small lists of less than 6 to 10 items you can use a simple Choose function (Example 5.)
=Choose(Randbetween(1,6),”Item 1″, “Item 2”, “Item 3”, “Item 4”, “Item 5”, “Item 6”)
VLookup
Using VLookup (Example 6.)
=Vlookup(Randbetween(1,List Length), List, 2)
Index
Using Index (Example 7.)
=Index(List, Randbetween(1, Counta(List) ))
Numbers
Small Random List of Numbers
Random from a small list of numbers (Example 8.)
=Choose(Randbetween(1,6), Numb 1, Numb 2, Numb 3, Numb 4, Numb 5, Numb 6 )
Note that the numbers:
- Don’t have to be in any order,
- Can be integers, negatives or contain decimals
- Can be repeated
eg: =Choose(Randbetween(1,6), 18, 21, -19, 36.4, 18, 24)
Random Integers
Return Integers between Start and Finish (Example 9.)
=Randbetween(Start, Finish)
=Randbetween(50, 100)
Will return an Integer between 50 and 100
Random Numbers
=Rand()
Will return a random number between 0 and 1
=Round(Rand()*100, 2)
Will Return Numbers between 0 and 100 with 2 Decimal places (Example 10.)
Random Numbers Based on a Distribution
=Norminv(Rand(), Mean, SD)
Will return a random number between 0 and 1 based on a distribution of Average = Mean and Standard Deviation = SD
=Norminv(Rand(), 50, 17)
Will return a random number between 0 and 100 based on a distribution of Average = 50 and Standard Deviation = 17, (Example 11.)
Random Numbers Fitting a Trend
If your distribution has to match a trend add a Random component to the Trends equation (Example 12.)
Y=mX+c
= rand() * X + rand()*5
= rand() * A2 + rand()*5
True/False
Choose
Use Choose and Randbetween (Example 13.)
=Choose(Randbetween(1,2), True, False)
If
Use If and Rand (Example 14.)
=If(Rand()<0.5, True, False)
Combination Text and Numbers
The above techniques can be combined to make lists of Alpha Numeric Data
Say your business has a fleet of vehicles (TR=Truck, VN=Van, CAR=Car)
=Choose(Randbetween(1,3),”TR”,”VN”,”CAR”) & Text(Randbetween(1,15),”0#”)
Will randomly choose 1 of “TR”,”VN”,”CAR” and add a random number between 1 and 15 to it format with a leading 0, eg: TR05, (Example 15.)
Other Sources of Data
Random Data
There are a number of web sites where Random Data is available.
http://www.fakenamegenerator.com/order.php
http://www.generatedata.com/#generator
http://www.melissadata.com/lookups/
Open Source Data
There are a number of web sites where Open Source Data is available.
http://www.readwriteweb.com/archives/where_to_find_open_data_on_the.php
Function Used:
Rand: Returns a random number between 0 and 1.
Randbetween: Returns a random Integer between lower and upper limits. Pre Excel 2007 Randbetween was only available through installation of the Analysis Toolpak (Thanx Luke).
Norminv: Returns the inverse of the normal cumulative distribution. That is it returns the X value from a Normal Distribution that has a know Mean and Standard Deviation where the a known cumulative percentage is supplied.
Choose: Choose an item from a list of up to 254 items.
Vlookup: Lookup the matching value from a list and return a data item from another column from the same location.
Index: Retrieve an items from a defined location within a range.
Text: Displays a number as Text with a defined format.
Other Uses of Random Functions
Of course the techniques shown here don’t have to be used for setting up Dummy Data.
One area where Random numbers is used is in Monte Carlo Simulation. This has been discussed at Chandoo.org at Data Tables and Monte-Carlo Simulations in Excel a Comprehensive Guide
Techniques
The techniques described above are all shown with a worked example in the attached Examples File or the Examples File 2003 ver
Limitations in Pre Excel 2007 versions
The Excel function, Randbetween, was only introduced in Excel 2007. As such the exaples above will only work in 2007/10.
However a simple alternative is available
Randbetween(Low, High) = Low + Int(Rand()*(High-Low))+1
Randbetween(90, 100) = 90 + Int(Rand()*10)+1
Examples using this approach are shown in the 2003 Version of the Examples files above.
How have you made Dummy Data or used the Random Functions?
How have you made Dummy Data or How have you used it ?
How have you used Random Numbers in your workbooks ?
Let us know in the comments below:
37 Responses to “Quickly Change Formulas Using Find / Replace”
Chandoo,
this is a really cool stuff what I use quite often. In addtion this method also could be a good choice to switch the reference type of the formulas from relative to absolute or vice versa. (just simply replace the $ in the same way).
Andras
@Andras: you are right, we can use find / replace to change references, reference types etc. Now, only if they had regex in find/ replace, we could so much more 🙂
@Tony Rose: Thank you. This is very useful and powerful feature. I even use it for cleaning up data. While formulas are good, they are not the solution for every problem. Often when I need more powerful cleanup / changing, I copy paste the stuff to text editors like notepad++ and then use their find/replace to do the dirty task.
What if i have to change the formula from ='Analysis'!C1 to 'Analysis 1'!C1?
I tried doing it using Find /Replace but could't. Encountered some errors.
And is there a way to change this using VBA???
Hi,
Did you ever get a reply to this?
Thanks
Ollie
to make your life easier, suggest you to avoid (Space) in worksheet names whenever possible. Consider (underscore) instead.
As the first formula wouldn't have the single apostrophes (since there's no space) need to include that in replace. So, search for:
Analysis
and replace with:
'Analysis 1'
This could be the most useful tips I've seen in a while. I use this all the time and can instantly change 400 formulas with a few clicks. Like so many other functions in Excel, I don't know what I would do without this one.
Keep 'em coming!
[...] on formulas: 5 areas where mouse kicks keyboard’s butt | Edit formulas in bulk using Find / Replace | Excel Formulas Online [...]
THANKS BRO
You, sir, are a god among men...
This is really cool. Your just save me hours of work. Thanks.
Thanks so much for this fix! It saved me tons of work. I'm muddling my way through and this really helped!
Oh... My... God!
This tip just saved me about 2 hours every month! I can't believe how easy it is to use. Now, can somebody tell me who I should call to get a refund for the previous 100 hours I spent manually changing formulas cell by cell?
Thanks so much!
THANK YOU!!!
THANK YOU!!!!
You saved me hours, I had a sheet that has more than 500 formulas, and i needed to replace the year in all of them, you saved me hours
Awesome info on replacing cell addresses in formulas. I have never heard about Ctrl+` before. Thank you!
I have something inside a formula like:
=sum(A1, A2*10) all over I now need to get rid of the *10 {=sume(A1, A2)} I thought to use the find replace trick above but with a blank in the replace but it then outputs just zeros. I thought I could trick it by doing *1 but then it just turns into =*1) with none of my references. Does anyone have an idea how to do this?
The Ctrl+ trick is cool.
@T
Instead of replacing with a blank try replacing
*10)
with
)
Thank you! This literally will save me hours and hours of time, and that's without losing my sanity in the process!
I have Sheet(1), Sheet(2), Sheet(3), etc ... Sheet(100).
Then there's a summary tab where I want to recap information on all those different sheets. Is there anyway to create a formula on the Summary tab to get ='Sheet(1)'!B$29 copied down for all 100 sheets without having to change each sheet # within the formula by hand?
@Brigitte
If you have a list of the sheet names in A2:A100
In B2: =INDIRECT("'"&A2&"'!$B$29")
Copy down
or if you don't have a list of the sheets names you can make it up on the fly
=INDIRECT("'sheet("&ROW()-1&")'!$B$29")
Copy down
Thanks for the suggestion. However, I copied your formula right back to my file and it didn't work. So I did it another way. I put the tab/cell reference in one cell and then did an =INDIRECT() to capture that information.
K2="'Sheet("&L2&")'!B$29" which has a value of 'Sheet(1)'!B$29
B2=INDIRECT(K2) which now has a value of 40 (contents on Sheet(1).
Thank you!!!!
Thank you ..
Hi, Out of all the formulae, I wish to replace the formula which has generated 0 value with blank space? I am unable to do it with find and replace function,
Please suggest.
Thanks.
Chandoo, you literally just saved me about 2 hours of work. I had a document with a daily report in two formats. The second formate just linked to all the appropriate cells in the other format (different sheets). This was 180 references that needed to be changed and I had to make this for a 4 week period (aka 28 different sheets at 180 references to change per sheet).
Thanks so much.
I have tried this way and without using the Ctrl-` formula view
Either way, I am trying to do something simple, but it won't let me.
I have a bunch of cells with a simple math formula like
=-(0.5*20)
various values in each cell, multiplied by 20
I simply want to change the multiplier globally from 20 to 25. But when I tell it to find *20 and replace it with *25, it replaces the entire cell contents with *25, rather than just replacing the *20 portion of the cell contents.
Can anyone assist with this? Seems so simple, but Excel isn't letting me do it.
Search/Replace 20 or 20) with a cell Reference eg A1 or A1)
Then put the value 25 in A1
By using a * in the search it replaces all the text
how to find a specific cell's value in a column & replace replace it with another cell value i actually need a method to replace a data in ca column and replace with the value i have in a specific cell can i give a [ location ] of data to what i need to find and then give row or column range to where i need to find and the given value & then give a [ location ] of data to what i want to be replace with the find and replace by row & column range & than by specific criteria and than by specific location.
please help.
how to find a specific cell’s value in a column & replace replace it with another cell's value.
i actually need a method to find a specific cell's data in a column and replace it with the value i have in a specific cell.
can i give a [ location ] of data to what i need to find and then give row or column range from where i need to find the given value & then give a [ location ] of data to what i want to be replace with.
find and replace by row & column range & than by specific criteria and than by specific location.
please help.
how to find a specific cell’s value in a column & replace it with another cell’s value.
i actually need a method to find a specific cell’s data in a column and replace it with the value i have in a specific cell.
can i give a [ location ] of data to what i need to find and then give row or column range from where i need to find the given value & then give a [ location ] of data to what i want to be replace with.
"find and replace by row & column range & than by specific criteria and than by specific location."
in more than 100 sheets in entire workbook
please help.
This is a great tool, does anyone knows an easiest way??
I'm working with a system that has over 59000 references... so every time the replace all is activated. I lose an entire day.
i actually needs to find cell number "D12" in column "D" and replace with Cell Number "B8" for example
find what = Cell Number "D12" John McNamara
find Where = in Column "D"
Replace with = Cell Number "B8" Bieber D'Souza
Replace Range = Column "D"
In which Sheet = All Sheets in Work Book (more than 100 Sheets)
Note: in every Sheet Cells Number "D12" & "B8" containing Different Employ Name but the find rang and replace rang are same in every sheet and find what cell number and replace with cell number are same also.
please help!
thank you. saved lot of time.
Thank you from the bottom of my heart!
Hi, I am trying to figure out how to use RE to find and replace several values in a column. Using find and replace does not work because of the values I am working with. I have a column with hundreds of rows that have a description of several operating systems and other info, which looks like this: Windows Server 2008 R2 Member Server Security Technical Implementation Guide; Windows 2008 Member Server Security Technical Implementation Guide; Solaris 10 10 SPARC SECURITY TECHNICAL IMPLEMENTATION GUIDE; and Windows Windows 2003 Member Server Security Technical Implementation Guide.
I need to be able to find and replace (or basically curtail the descriptions) to be Windows 2008 R2; Windows 2008; Windows 2003; and Solaris 10. BUT when I run find and replace with just *2008*, it finds every instance, including the ones with R2 at the end. I need it to only change the ones with 2008 to Windows 2008 and the ones that have 2008 R2 to Windows 2008 R2. I know it is possible, but I have no clue on how to write a macro to do this.
Thanks for your help,
Gerard
Wickedly efficient workaround. Excel really is a powerhouse program, all you have to do is dig into it. Ctl ~ exposes the formulas, and Ctl H allows for the multi edit. Brilliant, Chandoo!