Traders' Roundtable

Does anyone has any idea on the reliability of yahoo's data on historical stock prices? Thanks...

Louis

i use yahoo data for my stock analysis. if you scroll to the bottom of finance.yahoo.com you'll notice that they get their data from CSI. i use CSI data for futures and decided not to buy stock data from them because i assume that the yahoo data is the exact same data. so far i haven't noticed any problems with the yahoo feed but i'd be curious to see if anyone out there gets stock data directly from CSI and has noticed any discrepancies.

Hi,
there are some data errors, but not many. You can scan for huge % moves and remove the ones that are not real.

Also, I think that the database is subject to survivorship bias.

janvir17 wrote:so far i haven't noticed any problems with the yahoo feed but i'd be curious to see if anyone out there gets stock data directly from CSI and has noticed any discrepancies.

You may want to read the post that indicates otherwise:

http://www.wealth-lab.com/cgi-bin/Wealt ... 1&start=11

Thanks for the info guys... another question is... do any of you know how Yahoo adjust for dividends?... From their data, it seems like they are just subtracting the whole historical series by any new dividends, almost like the way one back-adjust futures data.

However, it does not seem to be the case... since the differences between the adjusted close and the actual close (taking into account any splits) is not exactly the same as the dividends, or rather, the cumulative dividends. Well, to be honest, I would not have thought this is best way to go about it anyway, since we need to take into consideration the time-value of the dividends, but that gets awfully complicated.

So, I guess my next question is... is there a best practice for adjusting historical stock prices for dividends?

Cheers,
Louis

Splits, dividends, mergers, liquidations...

I don't use free data to test anything because there are too many factors. I find a good vendor and gladly pay them to sort it out.

after reading the thread that TK pointed us to, and considering the pain in the ass that it is to screen and analyze stocks manually, last week i subscribed to CSIs stock database. it's awesome. for those of you out there who are screening stocks with either IBD or one of the web sites like stockcharts.com, i highly recommed paying the $200 odd dollars for CSI's database. they have a market scanning feature that has a number of indicators pre-programmed, plus you can program your own custom indicators directly into the application. my IBD subscription is history once it runs out. as a moderate, i was getting a little sick of their fanatical right-wing tirades anyway...