Trusting Excel

[less42]

I've been having an on-going debate with several of my co-workers about "trusting" Excel. She always double checks the figures in Excel for fear that they are not adding correctly and doesn't use Excel templates or formulas.

Is there any merit to this?

 

[NateO]

Hello and welcome to the board.

Like a simple =Sum(a1:a10)? Sounds like paranoia?

I don't know, I'll test Apps when I develop them, but I won't test them over and over again once I'm pretty sure it's producing the intended results.

E.g., at one point I did take the time to tie-out the NPV() function, but I now know how to use it and produce the correct results with it.

There are certain functions that I use a lot that I simply would not want to live without, e.g., SumProduct().

 

[PaddyD]

Hi - welcome to the board!

Short answer - no

Longer answer - excel is perfectly capable of doing complex maths & no-one should be double checking if it's got (24 * 456 ) right. There are occasions (usually when dealing with numbers with many decimal places) where things can get a bit odd (specifically 'cos excel only has decimal precision to 15 places), but the sort of person who knows about this & might be worried is not the sort of person who wont use the templates or formula 'cos the don't 'trust' them.

sounds like someone wanting to make work for themselves in case somebody noticed their position wasn't actually required

 

[Oaktree]

Your co-worker uses Excel but doesn't use its formulas? Does s/he use a slide-rule to double check the calculations?

The overwhelming majority of the time, Excel will be spot on so long as there is no user error (such as leaving calculation on manual and not forcing a recalc or having Excel return what you typed instead of what you were thinking ). As Paddy pointed out, there can be exceptions to this ----but, if s/he is really concerned about those exceptions, s/he could always read about the limitations of Excel instead of discrediting the whole application. After all, more people in the world trust Excel's calculations than your co-worker's slide-rule hand calculation

 

[fairwinds]

I've been involved in a pretty serious mistake where numbers consolidated from different files for a quotation were summed and not all were included in the sum (formatting issue) This incident almost put a company out of busines.

I always double check that kind of calculations.

 

[gearcutter]

Hi, many years ago I did all my calculations by long hand,I did'nt trust calculators, then I started to work for myself. A calculator suddenly became a trusted tool. Excel is brilliant, it's whether you programme it correctly.

 

[litrelord]

Sounds more like not trusting themselves than not trusting excel. Having faith that you’ve done any work correctly comes with time. The number of things I double check when I’ve done them has always steadily decreased. There are of course some things which I’ll always double check. Of course it depends how you work. I’ve been caught out by not checking because calculation was set to manual instead of automatic. If I’d have double checked I would have noticed. But the extra time taken to correct the very occasional human error mistake is more than made up by the time saved by having faith in your abilities.

 

[doco]

I recently read a book 'The Difference Machine' http://www.amazon.com/gp/product/06...102-8818894-2500119?s=books&v=glance&n=283155 About Charles Babbage and his quest to build a 'computer'. It seems insurance companies and the like would hire armies of 'calculators' to calculate actuaries and log scales, etc in his day; for which as much as 30% were in error yet were used quite effectively(if you knew what you were doing to start with - an oftentimes overlooked factor ).

I have read many articles that state more than 80% of all spreadsheets contain error; which, like in Babbage's day, are traced to human error.

It seems Excel is not immune to the GIGO (garbage in garbage out) vector any more than hand, calculator and or computers are.

BTW: We have people here who still make 10 key calculations then enter the results in Excel - now this is just plain lazy stupid! IMHO of course :wink:

 

[Engineer Joe]

I do more than double check my figures. I actually take both of my hands and count out each calculation. It gets tricky when decimals come into play, because then i start bending my fingers slightly to imply the correct fraction. when using exponents, I've found it handy to have a co-worker come into the office and either tell him/her to remember what iteration I'm on, or to lend me the use of his/her fingers. I prefer using their fingers, that way I can always see what's going on, and I know they're not gonna screw it up.

I know what you're thinking, but trust me, it's worth the little bit of extra effort at the office so that I can go home and rest easy knowing that I've got all my ducks in a row.


jpc

P.S. - Sliderules??? You trust those things?

 

[DBA]

Is there any merit to this?

Yes, if the sheets are unprotected and the users are prone to typing over formulas.