|
PureBytes Links
Trading Reference Links
|
Yahoo is a very useful and generous company.
They graciously host this and other useful usergroups, and their free
email service works better than Hotmail.
However, as Richard at http://www.premiumdata.net often points out,
accurate and up to date data is not Yahoo's thing. Below is a current
example for both these points:
http://chart.yahoo.com/d?a=0&b=1&c=2005&d=1&e=1&f=2005&g=d&s=%5Egspc
S&P 500 index data, available from Yahoo as at Mon 24 January 2005:
Date Open High Low Close Volume Adj. Close*
Jan-20-05 144.69 144.69 143.06 144.08 316,900 144.08
Jan-14-05 1,179.48 1,185.15 1,177.45 1,184.52 1,868,889,984 1,184.52
Late data, wrong data, and missing data. If Yahoo can get a major
index so so wrong, what chance for other data?
Let the buyer beware, indeed.
jose '-)
--- In Metastockusers@xxxxxxxxxxxxxxx, "Richard Dale" <richard@xxxx>
wrote:
> Hi Jim,
>
> HQuote is a Yahoo downloader. I've previously put together a list
> of the problems associated with these types of programs:
>
> 1. No delisted history - any system testing you do based on Yahoo
> data is subject to population bias. ie you can only test on the
> stocks that are currently listed.
>
> 2. Significant inaccuracies for any stock exchange that trades in
> increments less than 1c. This includes the Australian Stock
> Exchange (ASX), Singapore Exchange, some NASDAQ stocks and most
> OTCBB & Pink Sheet stocks.
> This happens because Yahoo's data is rounded to the nearest cent.
> For example, there are 14000 listed instruments on the ASX. Over
> 8000 of them are currently trading below 20c which means they move
> in either 0.5 or 0.1c increments. Since Yahoo only prices in cents
> this introduce VERY SIGNIFICANT inaccuracies. - eg. a 2.6c shown as
> 3c represents a 15% error).
>
>
> 3. Normal dividends are adjusted by subtracting all historical
> data by the dividend amount. Exchanges such as the ASX do not
> adjust price data for standard dividends. By diluting it the way
> they do, any technical analysis or backtesting no longer shows a
> correct % return, nor does it show a critical technical levels such
> as support and resistance.
>
> 4. No sector information - critical if you want to perform
> sector-based analysis. Also, there are multiple classifications
> systems in use (US - both GICS & DJ) - you need to ensure that your
> data aligns with your classification systems so you can easily
> compare a sector index to the right stocks.
>
> 5. Significant number of missing stock splits and other capital
> adjustments.
>
> 6. There is no guarantee that Yahoo will continue to supply data,
> especially to automated download programs. In Yahoo's Terms of
> Service, they have a clause which says "You agree not to reproduce,
> duplicate, copy, sell, trade, resell or exploit for any commercial
> purposes, any portion of the Service (including your Yahoo! I.D.),
> use of the Service, or access to the Service.". Companies that
> produce Yahoo downloaders are effectively exploiting the Yahoo
> service and are therefore in breach of the Yahoo Terms of Service
> and Yahoo may shut down these types of automated Yahoo downloading
> programs very easily.
>
> The best analogy I can use for data feeds is they are like a game of
> Chinese Whispers.
> http://www.chinesewhispers.com/chinesewhispers.php
>
> In the case of programs that extract data from Yahoo, the exchange
> sends data to Reuters. Reuters interpret the data, put it into
> their databases, then take an extract of the data and send it to
> Yahoo. Yahoo interprets the data, puts it into their database, then
> extracts it onto the Yahoo Finance web site. Then the downloading
> program obtains data from the Yahoo site, interprets it, and puts it
> onto the user's PC. If at any step of the above process, the
> interpretation is slightly incorrect then you have a
> discrepancy between actual events on the market and data you
> receive.
>
> So, whilst the Yahoo data is free to obtain from the Yahoo site, you
> need to determine what you really need from the data. If you're
> ever likely to want to view accurate historical charts (eg for
> system development / backtesting / historical interest) then the old
> adage "you get what you pay for" certainly applies here.
> Caveat emptor.
>
> Best regards,
> Richard Dale.
> Norgate Investor Services
> - Premium quality Stock, Futures and Foreign Exchange Data for
> markets in Australia, Asia, Canada, Europe, UK & USA -
> www.premiumdata.net <http://www.premiumdata.net/>
>
>
>
>
> _____
>
> From: jim [mailto:jimk_30045@x...]
> Sent: Friday, 21 January 2005 3:31 AM
> To: Metastockusers@xxxxxxxxxxxxxxx
> Subject: [Metastockusers] EOD Data Feed
>
>
>
> I need a new data feed..my tc2k gave me problems and i have stopped
> using that source..I saw Hquote on www...they certainly are
> reasonably priced,and a feed for tradestation as well..is anybody
> using this...comments good or bad would be appreciated...an can
> anyone give me any other good data source comments for
> Metastock...thanks.....
------------------------ Yahoo! Groups Sponsor --------------------~-->
What would our lives be like without music, dance, and theater?
Donate or volunteer in the arts today at Network for Good!
http://us.click.yahoo.com/Tcy2bD/SOnJAA/cosFAA/zMEolB/TM
--------------------------------------------------------------------~->
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/Metastockusers/
<*> To unsubscribe from this group, send an email to:
Metastockusers-unsubscribe@xxxxxxxxxxxxxxx
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
|