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?'"

Comments

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=