DollarLink News -- January 31, 1998

Error Checking in DollarLink

Judging from the number of calls we get on this subject, it is useful to go over the way DollarLink treats bad incoming quotes.

Every time a new price quote for a symbol comes in, DollarLink compares it to the latest already-accepted price for that symbol. If the percent difference between these two prices exceeds a tolerance parameter, the new price is rejected.

The tolerance parameter can be changed by the user by running our SETUP utility. The default for the tolerance parameter is 20%.

If price error checking kicks in, an asterisk appears next to the price field on the quote pages to indicate the reason why this issue is not updating anymore. Thus, you do not have to wonder why all of a sudden this issue stopped getting quotes.

You can always disable or enable error-checking while running DollarLink by pressing Control+E key combination and then I while in text mode.

If you enable the error checking, DollarLink will ask you for a tolerance percent limit, i.e., if the percent difference is greater than that limit, DollarLink will reject an incoming price quote. This tolerance parameter can be between 1% and 200%.

If you disable the error checking, all incoming quotes will be accepted and the asterisk from error checking will disappear.

Note that changes invoked with Control+E are in effect only during the current session of DollarLink. To make changes permanent and always in effect, run SETUP (Part 1).

Also note that options, low-priced (under 2.00) quotes, custom indices and some datafeed indices do not get checked. That is because low-priced quotes, options and some datafeed indices (such as $TICK or $TRIN or volume-dependent indices) can exhibit wild oscillations; custom indices are not prices, they are calculated from prices.

Our error checking even works with stock splits because DollarLink bypasses error checking for the very first quote of the day. Usually stocks don't split in the middle of the day, so the first quote -- at the new split price -- gets accepted.

Monitoring Error Checking

You can tell DollarLink to show you the quotes it is rejecting due to error checking. This can help you spot the situations where DollarLink appears to reject valid prices. Press Control+E and then M (for Monitor). The rejections will show up at the bottom of the screen in text mode and in the lower left rectangle in graphics mode. This feature has a dual effect. First, if a symbol keeps reappearing on a regular basis with the same rejected price which seems reasonable, then maybe it really has changed a lot. Second, monitoring the rejections gives you a good idea of the effectiveness of numerical error checking.

Useful Financial Web Sites

There is an enormous number of financial Web sites on the Internet. Some, however, are more useful than others. We find the financial pages of Yahoo ( http://quote.yahoo.com ) to be the most comprehensive and useful.

Yahoo started out as an Internet search engine. After the company went public, Yahoo has been spending big bucks maintaining their Web site, especially financial information. They have all kinds of instant quotes, domestic and international business news, fundamental information on companies, historical charts, user-created portfolios, etc. The way the site is organized and the way the information is displayed shows that they must have a large staff with vast financial experience working on this site. It is a truly helpful tool. And it's free.

Another useful site is the charting page of Quote.com : http://www.quote.com/cgi-bin/jchart-form?genApplet=yes

This fairly new addition to Quote.com's site was recommended to us by a DollarLink user.

When you first go to this site, it starts a small, Java-based application inside your Web browser which displays an intraday chart of the symbol of your choice. Usually charts of stocks and commodities will be delayed 15 minutes. If you pay a fee to Quote.com, then they can be real-time. There is, however, one notable exception:

In order to promote it, the Chicago Mercantile Exchange is currently giving away the real-time quotes of the S&P mini-contract. Thus, the Quote.com chart can display a free real-time intraday chart of this contract. If you enter ES8H into the chart, you can have a simple but fast real-time chart for the S&P. This can be a very useful tool during a volatile day in the market.

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