Why You Shouldn't Use Spreadsheets For Important Work

An anonymous reader writes "Computer science professor Daniel Lemire explains why spreadsheets shouldn't be used for important work, especially where dedicated software could do a better job. His post comes in response to evaluations of a new economics tome by Thomas Piketty, a book that is likely to be influential for years to come. Lemire writes, 'Unfortunately, like too many people, Piketty used spreadsheets instead of writing sane software. On the plus side, he published his code ... on the negative side, it appears that Piketty's code contains mistakes, fudging and other problems. ... Simply put, spreadsheets are good for quick and dirty work, but they are not designed for serious and reliable work. ... Spreadsheets make code review difficult. The code is hidden away in dozens if not hundreds of little cells If you are not reviewing your code carefully and if you make it difficult for others to review it, how do expect it to be reliable?'"

So what's the alternative?

[Cyberax]

So what's the alternative? There are no good and easy to use software packages to create simple data-intensive apps. The closest alternative was VB6 and if I had to chose between it and Excel, I'd choose Excel any day of the week.

A Formula only an Actuary could Love

[turp182]

There are no corporate secrets below, but I stumbled upon this formula in an actuarial spreadsheet (I'm a developer with an actuarial education).

The only way this logic could be verified is by breaking the single formula into 20+ different cells with more simple calculations.

And of course it is in several thousand cells, bringing any computer at all to its knees during calculation.

A good example of how not to use Excel (but the actuaries don't have access to IT prototyping or core development).

=IF(F6="050",tiers!$D$21+IF(AND(F6="050",OR(E6="W",E6="X")),tiers!$D$29-tiers!$D$26+VLOOKUP("N"&100&VLOOKUP(L6,tiers!$B$38:$C$49,2,0)&"N/A"&M6/12&"/"&N6&"0-"&R6/1000&C6*1,tiers!$L$2:$W$20969,12,0),IF(OR(E6="W",E6="X"),VLOOKUP("N"&F6*1&VLOOKUP(L6,tiers!$B$38:$C$49,2,0)&"N/A"&M6/12&"/"&N6&"0-"&R6/1000&C6*1,tiers!$L$2:$W$20969,12,0),IF(AND(F6="050",E6="P",M6=36,N6=60),tiers!$D$29-tiers!$D$26+VLOOKUP("E"&100&VLOOKUP(L6,tiers!$B$52:$C$55,2,0)&"N/A"&M6&"/"&N6&VLOOKUP(R6,tiers!$B$57:$C$59,2,0)&C6*1,tiers!$L$2:$W$20969,12,0),IF(AND(E6="P",M6=36,N6=60),VLOOKUP("E"&F6*1&VLOOKUP(L6,tiers!$B$52:$C$55,2,0)&"N/A"&M6&"/"&N6&VLOOKUP(R6,tiers!$B$57:$C$59,2,0)&C6*1,tiers!$L$2:$W$20969,12,0),IF(AND(F6="050",E6="P"),tiers!$D$29-tiers!$D$26+VLOOKUP("E"&100&VLOOKUP(L6,tiers!$B$52:$C$55,2,0)&"N/A"&M6/12&"/"&N6&VLOOKUP(R6,tiers!$B$57:$C$59,2,0)&C6*1,tiers!$L$2:$W$20969,12,0),IF(E6="P",VLOOKUP("E"&F6*1&VLOOKUP(L6,tiers!$B$52:$C$55,2,0)&"N/A"&M6/12&"/"&N6&VLOOKUP(R6,tiers!$B$57:$C$59,2,0)&C6*1,tiers!$L$2:$W$20969,12,0),IF(AND(F6="050",E6="*",M6=6),tiers!$D$29-tiers!$D$26+VLOOKUP(B6&100&VLOOKUP(L6,tiers!$B$38:$C$49,2,0)&IF(Q6=48,"0-4","6-10")&M6&"/"&N6&"0-100"&C6*1,tiers!$L$2:$W$20969,12,0),IF(AND(E6="*",M6=6),VLOOKUP(B6&F6*1&VLOOKUP(L6,tiers!$B$38:$C$49,2,0)&IF(OR(L6="PPH08",L6="PTH08"),"0-9",IF(Q6=48,"0-4","6-10"))&M6&"/"&N6&IF(R6=125000,"100-125","0-100")&C6*1,tiers!$L$2:$W$20969,12,0),IF(AND(F6="050",E6="*"),tiers!$D$29-tiers!$D$26+VLOOKUP(B6&100&VLOOKUP(L6,tiers!$B$38:$C$49,2,0)&IF(OR(L6="PPH08",L6="PTH08"),"0-9",IF(Q6=48,"0-4","6-10"))&M6&"/"&N6&IF(AND(OR(L6="PPH08",L6="PTH08"),R6=100000),"0-100",VLOOKUP(R6,tiers!$B$64:$C$70,2,0))&C6*1,tiers!$L$2:$W$20969,12,0),IF(E6="*",VLOOKUP(B6&F6*1&VLOOKUP(L6,tiers!$B$38:$C$49,2,0)&IF(OR(L6="PPH08",L6="PTH08"),"0-9",IF(Q6=48,"0-4","6-10"))&M6&"/"&N6&IF(AND(OR(L6="PPH08",L6="PTH08"),R6=100000),"0-100",VLOOKUP(R6,tiers!$B$64:$C$70,2,0))&C6*1,tiers!$L$2:$W$20969,12,0),"ERROR")))))))))),IF(AND(F6="050",OR(E6="W",E6="X")),tiers!$D$29-tiers!$D$26+VLOOKUP("N"&100&VLOOKUP(L6,tiers!$B$38:$C$49,2,0)&"N/A"&M6/12&"/"&N6&"0-"&R6/1000&C6*1,tiers!$L$2:$W$20969,12,0),IF(OR(E6="W",E6="X"),VLOOKUP("N"&F6*1&VLOOKUP(L6,tiers!$B$38:$C$49,2,0)&"N/A"&M6/12&"/"&N6&"0-"&R6/1000&C6*1,tiers!$L$2:$W$20969,12,0),IF(AND(F6="050",E6="P",M6=36,N6=60),tiers!$D$29-tiers!$D$26+VLOOKUP("E"&100&VLOOKUP(L6,tiers!$B$52:$C$55,2,0)&"N/A"&M6&"/"&N6&VLOOKUP(R6,tiers!$B$57:$C$59,2,0)&C6*1,tiers!$L$2:$W$20969,12,0),IF(AND(E6="P",M6=36,N6=60),VLOOKUP("E"&F6*1&VLOOKUP(L6,tiers!$B$52:$C$55,2,0)&"N/A"&M6&"/"&N6&VLOOKUP(R6,tiers!$B$57:$C$59,2,0)&C6*1,tiers!$L$2:$W$20969,12,0),IF(AND(F6="050",E6="P"),tiers!$D$29-tiers!$D$26+VLOOKUP("E"&100&VLOOKUP(L6,tiers!$B$52:$C$55,2,0)&"N/A"&M6/12&"/"&N6&VLOOKUP(R6,tiers!$B$57:$C$59,2,0)&C6*1,tiers!$L$2:$W$20969,12,0),IF(E6="P",VLOOKUP("E"&F6*1&VLOOKUP(L6,tiers!$B$52:$C$55,2,0)&"N/A"&M6/12&"/"&N6&VLOOKUP(R6,tiers!$B$57:$C$59,2,0)&C6*1,tiers!$L$2:$W$20969,12,0),IF(AND(F6="050",E6="*",M6=6),tiers!$D$29-tiers!$D$26+VLOOKUP(B6&100&VLOOKUP(L6,tiers!$B$38:$C$49,2,0)&IF(Q6=

Re:What he's really saying is

[jythie]

To be fair, they have their place. They are excellent tools for creating a table of data with a chart that can be emailed to other people and read.

Sadly, one of the big selling points for spreadsheets is their application. Pretty much any computer being used for work will have something that can read and display excel spreadsheets, you can send one to anyone and not have to worry about what they have installed. Then again you can get the same level of compatibility by outputting PDFs from matlab or something slightly saner like that....

Re: What he's really saying is

[Ol Olsoc]

Just got back from a meeting where I was explaining relational databases. No one really got it, but the Excel expert thought I was full of shit.

Well, I sort of am, but not for that reason.

There is nothing worse than trying to get a spreadsheet person up and running on relational databases. They argue with you about every point, then they freak.