Comments on: Working with numbers

By: lupi

lupi — Thu, 17 Nov 2011 15:09:29 +0000

I said I’d welcome feedback, and I do – obviously I’m not the only person who’s sensitive to these issues! Thank you all for your comments.

By: Mark

Mark — Tue, 08 Nov 2011 17:59:56 +0000

I love the line, “leave out as much detail as you can”.

And I generally love this article. My one dissent is not so much against what is said here, but a common misuse of the principle. If you are providing estimates NOT in the text of an analysis, but in something like detailed tables, rounding is not the ideal way to tell data users about the accuracy of your estimate. Particularly if the data users are going to use your data for other analyses.

An example: If your reasonably unbiased estimates of average earnings for two groups are $12,395 and $9,637, it is much more meaningful to take an income ratio of those two numbers rather than of $12,000 and $10,000, even if 2 standard errors > $500. This is even more so if the analysis being done by a data user is going to look at a number of such ratios over time or over different groups.

It is always difficult to prevent misuse of data, but suppressing it is not a good answer.

By: Brad Smith

Brad Smith — Tue, 08 Nov 2011 16:03:21 +0000

Helpful article. Thank you.

In the first table the implied decimal points shift to the left when going from double to single digits. All of the decimal points in a column, real or implied, should line up.

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By: Scott Hendrickson

Scott Hendrickson — Sat, 05 Nov 2011 15:12:43 +0000

Part of the problem is that common tools don’t support paying attention to and displaying significance. MS Excel does a poor job at this as the easiest choice there is to give all of your numbers the same number of decimal places. The constant-decimal-places idea applies best to money, best I would argue that if you are talking about many millions of dollars in any real situation, you have lost track of counting individual cents and so they don’t really mean anything there either. And as you note, calculators display a lot of digits, leading users to think they mean something.