On 4/2/20, Raul Miller <[email protected]> wrote: > One other thing -- after sleeping on this, I realized I had two > conflicting views about negative numbers in the stock values you were > working with: > (*) One is that negative numbers may appear in the data. > (*) The other is that negative numbers do not appear in the data. > Obviously, these cannot both be true. But the implementation should be > changed to fit whichever is the correct statement: ... > If negative numbers do not appear in the data, the whole elaborate > date cleaning process should be eliminated ...
Stock prices are never negative because they show value. If prices ever reach zero, the stocks are worthless. In other words, stock prices are always non-negative. However, negative numbers *can* occur, for example, in currency markets (and their quoted "prices"), where you deal with *ratios* (comparisons) between currencies, not absolute values. An example might be the EURUSD market, where the value comparison is between the Euro and the US Dollar. In general, this is why exchange rates can vary from day to day when you travel internationally and convert currencies at borders. But the table I'm dealing with is 3,000 *stocks*, so negative numbers don't apply. > I hope this helps, Thanks--I appreciate your help! Harvey ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
