The steps taken to fix an R problem.

Task

To prepare for the Portfolio Probe blog post called “Implied alpha and minimum variance”, I tried to update a matrix of daily stock prices using a function I had written for the purpose.

Error

When I tried to do what I wanted, I got:

> univclose130518 <- pp.updateclose(jjuc[,1:5])
done with: MMM  ABT  ANF  ACE  ACN  
Error in if (beg > end) stop("Start date must be before end date.") : 
  missing value where TRUE/FALSE needed

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How to have a better chance of a good outcome.

Making mistakes

There’s been a lot of talk recently about data analysis problems with spreadsheets.  If you’ve not stuck your head out of your cave lately, then you can catch some of the discussion by doing an internet search for:

Reinhart Rogoff

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