Re: FinancialData errors
- To: mathgroup at smc.vnet.net
- Subject: [mg120604] Re: FinancialData errors
- From: DrMajorBob <btreat1 at austin.rr.com>
- Date: Sat, 30 Jul 2011 06:03:36 -0400 (EDT)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- References: <201107222344.TAA28525@smc.vnet.net> <j0fos4$8p6$1@smc.vnet.net>
- Reply-to: drmajorbob at yahoo.com
> Prices do vary continuously, they don't stay the same for a whole day, > At the moment you bought it was 10.36. At the moment the data source > was sampled it was 10.23. Usually historical data use the closing > price, AFAIK. I see nothing strange in this. Nonsense. It's a mutual fund, as you can see from its name. It has one price, exactly once a day. I can look up that price at Yahoo! Finance, and it agrees with what the fund company charged me on that day. Check Feb 10th on the following page: http://finance.yahoo.com/q/hp?s=JANFX&d=6&e=29&f11&g=d&a=1&b=16&c10&z=66&y=66 where open, high, low, and close are all the same -- namely, $10.36. I JUST noticed the last column on that page says the "adjusted" close was $10.23, and that's what FinancialData returned -- part of a possible explanation -- but: a) There was no dividend or split on that day or any day nearby, b) NONE of the numbers in that column make any sense, c) For most days and/or most funds, FinancialData returns the unadjusted close, so there's no consistency, and d) I want the price I paid, not an "adjusted" number, even if it made sense. > If a difference of less than 2% in the historical market data > influences your algorithms, I won't trust your conclusions. :) I want to input the dollars I contributed and compute the shares I bought, to the same 3 to 4 digits that the fund companies compute it, in order to simplify "buy" and "sell" functions -- to save me time when entering trades. 2% is far too much error to do that. Ending with the wrong number of shares in my account -- because of days when the price comes back wrong from FinancialData -- is unacceptable. It makes the share and dollar balance wrong, the internal rate of return wrong, etc. I'm contributing $100 to my IRA 60 times a year, plus occasional transfers among the funds I hold, so simpler "buy" and "sell" functions seem worthwhile, if it were possible... which, with these errors, it is not. And regardless, whether I need perfection or not, the "curated" data is simply wrong. Bobby On Fri, 29 Jul 2011 03:48:42 -0500, Pierpaolo Bernardi <olopierpa at gmail.com> wrote: > On Fri, Jul 29, 2011 at 10:41, DrMajorBob <btreat1 at austin.rr.com> wrote: >> FUNNY STORY: Here is Tech Support's non-response to my problem, >> described >> farther down: > >> I've found a new (to me) species of error in FinancialData. >> >> One example is the price of the following stock on Feb 10, 2011: >> >> s = "JANFX"; >> FinancialData["JANFX", "Name"] >> FinancialData["JANFX", {{2011, 2, 9}, {2011, 2, 11}}] >> >> "Janus Flexible Bond Fund D Shar" >> >> {{{2011, 2, 9}, 10.25}, {{2011, 2, 10}, 10.23}, {{2011, 2, 11}, >> 10.24}} >> >> As you see, FinancialData says the price was 10.23. >> >> But I BOUGHT the stock through Janus Funds on that day, and the price >> was >> 10.36. >> >> Moreover, if I go to Yahoo's interactive price chart for the stock at >> the >> following page, 10.36 is the price I find: > > Prices do vary continuously, they don't stay the same for a whole day, > At the moment you bought it was 10.36. At the moment the data source > was sampled it was 10.23. Usually historical data use the closing > price, AFAIK. I see nothing strange in this. > >> So... where are the errors really coming from? >> >> This is not an astronomically large price or a Missing["Not Available"] >> price; it's within 2% of the correct price. But it's wrong. >> >> These errors make it very difficult to trust FinancialData for any >> useful >> purpose. > > If a difference of less than 2% in the historical market data > influences your algorithms, I won't trust your conclusions. :) > > Cheers -- DrMajorBob at yahoo.com
- References:
- Re: FinancialData still broken
- From: DANA DELOUIS <dana.del@gmail.com>
- Re: FinancialData still broken