We all have atleast one story of how that one time the boss / co-worker / classmate / cat ruined the carefully crafted excel spreadsheet by mucking up the formulas or disturbing the formatting. There are 3 very easy solutions to prevent this problem,
- Write an unleash_a_pack_of_wild_cats_when_someone_messes_with_the_file () macro: It is not an elegant solution, and cats are not very consistent, but it can work.
- Move to marketing department, you dont need to send excel files any more, just ppts. 😛
- Or, read this post and learn 10 awesome tips on how to boss proof your excel files.
So here is the list of 10 tips to make better excel spreadsheets. I suggest using all these tips for a perfect boss proof workbook.
Restrict The Work Area Few Columns and Rows
Not all spreadsheets have 256 columns and 65000 rows of data. So why show the entire grid when you can, say, just show the 44 rows and 23 columns in which the sales report is presented.
To restrict the work area,
- Select the first column you dont want to see (24th column) and press CTRL+SHIFT+RIGHT ARROW. Now Right click and select “Hide” option.
- Select the first row you dont want to see (45th row) and press CTRL+SHIFT+DOWN ARROW. Now right click and select “Hide” option.
Lock Formula Cells And Protect The Worksheet
Formulas are the most vulnerable part of an excel sheet. You accidentally edit something, say in payroll sparesheet, and you just gave 3200% bonus to someone in the organization. That is alright if that someone is a CEO of a bailed-out bank, but in all other cases, you end up spending a sweet afternoon trying to figure out what went wrong.
So, it is better to lock the workbook formulas and protect the worksheet so that no one accidentally erase the formulas or mess with them. To do this follow the steps in the illustration above.
You can use the same trick to lock the charts and other worksheet objects.
Freeze Panes So that Your boss Knows what she is Reading
Freeze panes is a very useful feature. It locks the important items on the top so even when you scroll down you still see them. (You can do the same for columns, thus seeing the first few column even when scrolling left).
Bonus tip: Use excel tables (new feature in Excel 2007) so that you dont need to freeze panes. Learn more.
Hide Un-necessary / Calculation Sheets
It is fairly common for excel workbooks to have tens worksheets, some with data, some with calculations, some with intermediate stuff and only one or two sheets with actual outcome (like a dashboard or a report).
There is no reason to think that all these worksheets should be visible all the time to the boss. While it makes sense to have the data and calculations visible so that someone can audit the worksheet, I am sure you dont want your boss to waster her time doing that. So here is a handy tip:
- Select all the worksheets other than the output sheets and hide them.
Hide Rows / Columns
If for some reason, hiding worksheets is not possible, you can still try hiding rows and columns. This is a very good way to prevent someone from accidentally messing a with a row of “really big and complicated formulas”.
Just select the rows / columns you want to hide and right click and select the “hide” option.
Include Cell – Comments / Help Messages
We all know bosses have a busy mind. They dont have time to remember (or know) every little thing. Heck, sometimes they dont even know what somethings are.
I suggest using cell comments and help messages to give right information / guidelines to the spreadsheet end user, like “enter your age in this cell”. They are easy to implement and totally non-intrusive.
- To include a cell comment, select the cell and press SHIFT+F2 and write the comment.
To include a cell message, select the cell, go to data validation, go to “input message” tab and type what you want.
Data Validations, Error Messages
Spreadsheets are complicated things that are carefully crafted with umpteen pre-conditions and assumptions. I am sure there is at least one excel file out there that will only work if a cat enters the input. But we are not talking about cats, the point is, it is important that right data is fed to the worksheet before the formulas (or charts or payroll macro etc.) can work. That is where data validation can help.
It is very easy to set up data validation in excel. Just select the cell and go to data validation (in Data ribbon / menu). There are several ways in which you can set up data validations,
- You can show an incell drop down box and ask users to pick from a list
- You can specify the type of data allowed (dates, times, numbers, text)
- You can specify the length of data
- You can specify the conditions on data (like between 2 numbers, less than a given date etc.)
- You can even use formulas to make your own data validations [example]
There are several examples of using data validation in this site. Go check.
Use Consistent Colors And Schemes
Anything looks better when it is consistent, even when it is internally screwed up. That same rule applies to excel workbooks as well. It will make your boss feel comfortable and relaxed to see an excel workbook with consistent colors and (simple) schemes.
I suggest using excel cell styles to define the styles for your workbooks. This ensures consistency and you dont have to spend after hours formatting the worksheets. Read more about cell styles.
Name and Color Worksheet Tabs Appropriately
It doesnt matter if you have designed an awesome excel dashboard, your boss can be still pissed because the sheet name is “Sheet 69”. That brings us to the last and final point.
Use appropriate names (and may be tab colors) for the worksheet tabs. This makes the navigation easy and boss proof.
Learn how to color excel worksheet tabs.
Before Closing The Workbook, Select Cell A1 On The Correct Sheet
Just before you finally save the workbook and e-mail it to the boss, make sure you are on the right worksheet (ie the dashboard or the report) and selected cell A1. The ensures that when the boss opens the workbook, she sees the right tab with right information, not some calculations or formulas.
That is all, you have just learned a handful of trick to impress your boss.
Share your boss proofing tricks for excel
Got an awesome idea that has been working on your boss? Share it with us in comments. I love to hear your stories and how you are using excel to further your career.
Be awesome, Learn few more excel tricks:
We at PHD have a simple goal – “to make you awesome in excel and charting”. Here is a list of articles I recommend reading if you are new here or just wanted to be more.
- 15 fun and exciting excel tips – who say spreadsheets are boring?
- 15 Excel formulas beyond IF() and SUM()
- 15 Excel productivity tips that you dont know
- 10 things about Excel 2007 that you should know to work better
- More articles on excel productivity
Dilbert cartoon from Dilbert.com
20 Responses to “Simulating Dice throws – the correct way to do it in excel”
You have an interesting point, but the bell curve theory is nonsense. Certainly it is not what you would want, even if it were true.
Alpha Bravo - Although not a distribution curve in the strict sense, is does reflect the actual results of throwing two physical dice.
And reflects the following . .
There is 1 way of throwing a total of 2
There are 2 ways of throwing a total of 3
There are 3 ways of throwing a total of 4
There are 4 ways of throwing a total of 5
There are 5 ways of throwing a total of 6
There are 6 ways of throwing a total of 7
There are 5 ways of throwing a total of 8
There are 4 ways of throwing a total of 9
There are 3 ways of throwing a total of 10
There are 2 ways of throwing a total of 11
There is 1 way of throwing a total of 12
@alpha bravo ... welcome... 🙂
either your comment or your dice is loaded 😉
I am afraid the distribution shown in the right graph is what you get when you throw a pair of dice in real world. As Karl already explained, it is not random behavior you see when you try to combine 2 random events (individual dice throws), but more of order due to how things work.
@Karl, thanks 🙂
When simulating a coin toss, the ROUND function you used is appropriate. However, your die simulation formula should use INT instead of ROUND:
=INT(RAND()*6)+1
Otherwise, the rounding causes half of each number's predictions to be applied to the next higher number. Also, you'd get a count for 7, which isn't possible in a die.
To illustrate, I set up 1200 trials of each formula in a worksheet and counted the results. The image here shows the table and a histogram of results:
http://peltiertech.com/WordPress/wp-content/img200808/RandonDieTrials.png
@Jon: thanks for pointing this out. You are absolutely right. INT() is what I should I have used instead of ROUND() as it reduces the possibility of having either 1 or 6 by almost half that of having other numbers.
this is such a good thing to learn, helps me a lot in my future simulations.
Btw, the actual graphs I have shown were plotted based on randbetween() and not from rand()*6, so they still hold good.
Updating the post to include your comments as it helps everyone to know this.
By the way, the distribution is not a Gaussian distribution, as Karl points out. However, when you add the simulations of many dice together (i.e., ten throws), the overall results will approximate a Gaussian distribution. If my feeble memory serves me, this is the Central Limit Theorem.
@Jon, that is right, you have to nearly throw infinite number of dice and add their face counts to get a perfect bell curve or Gaussian distribution, but as the central limit theorem suggests, our curve should roughly look like a bell curve... 🙂
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I'm afraid to say that this is a badly stated and ambiguous post, which is likely to cause errors and misunderstanding.
Aside from the initial use of round() instead of int(),.. (you've since corrected), you made several crucial mistakes by not accurately and unambiguously stating the details.
Firstly, you said:
"this little function generates a random fraction between 0 and 1"
Correctly stated this should be:
"this little function generates a random fraction F where 0 <= F < 1".
Secondly, I guess because you were a little fuzzy about the exact range of values returned by rand(), you have then been just as ambiguous in stating:
"I usually write int(rand()*12)+1 if I need a random number between 0 to 12".
(that implies 13 integers, not 12)
Your formula, does not return 13 integers between 0 to 12.
It returns 12 integers between 1 and 12 (inclusive).
-- As rand() returns a random fraction F where 0 <= F < 1, you can obviously can only get integers between 1 and 12 (inclusive) from your formula as stated above, but clearly not zero.
If you had said either:
"I usually write int(rand()*12) if I need a random number between 0 to 11 (inclusive)",
or:
"I usually write int(rand()*12)+1 if I need a random number between 1 to 12 (inclusive)"
then you would have been correct.
Unfortunately, you FAIL! -- repeat 5th grade please!
Your Fifth Grade Maths Teacher
Idk if I'm on the right forum for this or how soon one can reply, but I'm working on a test using Excel and I have a table set up to get all my answers from BUT I need to generate 10,000 answers from this one table. Every time, I try to do this I get 10,000 duplicate answers. I know there has to be some simple command I have left out or not used at all, any help would be extremely helpful! (And I already have the dice figured out lol)
Roll 4Dice with 20Sides (4D20) if the total < 20 add the sum of a rerolled 2D20. What is the average total over 10,000 turns? (Short and sweet)
Like I said when I try to simulate 10,000turns I just get "67" 10,000times -_- help please! 😀
@Justin
This is a good example to use for basic simulation
have a look at the file I have posted at:
https://rapidshare.com/files/1257689536/4_Dice.xlsx
It uses a variable size dice which you set
Has 4 Dice
Throws them 10,000 times
If Total per roll < 20 uses the sum of 2 extra dice Adds up the scores Averages the results You can read more about how it was constructed by reading this post: http://chandoo.org/wp/2010/05/06/data-tables-monte-carlo-simulations-in-excel-a-comprehensive-guide/
Oh derp, i fell for this trap too, thinking i was makeing a good dice roll simulation.. instead of just got an average of everything 😛
Noteably This dice trow simulate page is kinda important, as most roleplay dice games were hard.. i mean, a crit failure or crit hit (rolling double 1's or double 6's) in a a game for example dungeons and dragons, if you dont do the roll each induvidual dice, then theres a higher chance of scoreing a crit hit or a crit failure on attacking..
I've been working on this for awhile. So here's a few issues I've come across and solved.
#1. round() does work, but you add 0.5 as the constant, not 1.
trunc() and int() give you the same distributions as round() when you use the constant 1, so among the three functions they are all equally fair as long as you remember what you're doing when you use one rather than the other. I've proven it with a rough mathematical proof -- I say rough only because I'm not a proper mathematician.
In short, depending on the function (s is the number of sides, and R stands in for RAND() ):
round(f), where f = sR + 0.5
trunc(f), where f = sR + 1
int(f), where f = sR + 1
will all give you the same distribution, meaning that between the three functions they are fair and none favors something more than the others. However...
#2. None of the above gets you around the uneven distribution of possible outcomes of primes not found in the factorization of the base being used (base-10, since we're using decimal; and the prime factorization of 10 is 2 and 5).
With a 10-sided die, where your equation would be
=ROUND(6*RAND()+0.5)
Your distribution of possible values is even across all ten possibilities.
However, if you use the most basic die, a 6-sided die, the distributions favor some rolls over others. Let's assume your random number can only generate down to the thousandths (0.000 ? R ? 0.999). The distribution of possible outcomes of your function are:
1: 167
2: 167
3: 166
4: 167
5: 167
6: 166
So 4 and 6 are always under-represented in the distribution by 1 less than their compatriots. This is true no matter how many decimals you allow, though the distribution gets closer and closer to equal the further towards infinite decimal places you go.
This carries over to all die whose numbers of sides do not factor down to a prime factorization of some exponential values of 2 and 5.
So, then, how can we fix this one, tiny issue in a practical manner that doesn't make our heads hurt or put unnecessary strain on the computer?
Real quick addendum to the above:
Obviously when I put the equation after the example of the 10-sided die, I meant to put a 10*RAND() instead of a 6*RAND(). Oops!
Also, where I have 0.000 ? R ? 0.999, the ?'s are supposed to be less-than-or-equal-to signs but the comments didn't like that. Oh well.
How do you keep adding up the total? I would like to have a cell which keeps adding up the total sum of the two dices, even after a new number is generated in the cells when you refresh or generate new numbers.
So, how do you simulate rolling 12 dice? Do you write int(rand()*6) 12 times?
Is there a simpler way of simulating n dice in Excel?
I've run this code in VBA
Sub generate()
Application.ScreenUpdating = False
Application.Calculation = False
Dim app, i As Long
Set app = Application.WorksheetFunction
For i = 3 To 10002
Cells(i, 3).Value = i - 2
Cells(i, 4).Value = app.RandBetween(2, 12)
Cells(i, 5).Value = app.RandBetween(1, 6) + app.RandBetween(1, 6)
Next
Application.ScreenUpdating = True
Application.Calculation = True
End Sub
But I get the same distribution for both columns 4 and 5
Why ?
@Mohammed
I would expect to get the same distribution as you have effectively used the same function