What is a good rule of thumb for the number of significant digits to report? Preferably, the rule of thumb is given in a citable publication. I am particularly interested in a rule that does not consider the standard error or confidence interval of the estimate.
This is what I have found so far:
- http://www.sportsci.org/resource/stats/digits.html The general rule is "Most statistics need either two significant digits (the first two digits), or two decimal places when the number is less than 1.0". What do you think? Is this widely accepted?
There are a number of similar questions here, but they ask about a rule with a known standard error. Example: Number of significant digits to report .
If this helps, here is why I need this. I am writing a package to pretty-print values (https://github.com/prettyprint/prettyprint). Too many times, the output of an analysis is too hard to read, and therefore understand. Yes, you can make it pretty using
round, and that's basically what the package already does for you in the background.
I would like to make pretty-printing as easy as possible for the user. Sure, if they are willing to provide a standard error or confidence interval, I will use them to pretty-print the value (have not implemented this yet). However, to make it more usable for them, I also want some sensible rule when they do not provide a standard error or confidence interval. All they have to do is type
x is printed in a sensible and user-friendly way.