months of more current data stored on a hard drive. This current data can be accumulated, each day, a few hours after the market close. This downloaded data sits on the users hard drive to be seamlessly merged with the historical CD data to produce price charts at the snap of a mouse button.

Some data vendors also offer bimonthly or quarterly CD updates which, on installation, automatically remove the last two or three months worth of redundant data from ones hard drive. This automatic removal feature may be unwanted if it deletes data you had carefully cleaned of any bad values and replaces it with data that has not been as well scrubbed. Further details on data accuracy are described in the next section.

With respect to end-of-day data, the two means of product differentiation lie in price and file format. The general price range for daily downloading of an unlimited number of quotes runs between $20 and $50 per month.

Almost all vendors produce data files in ASCII format. Some produce data in Metastocks proprietary file format. For the user of Omega Researchs SuperCharts®, (SuperCharts® is a registered trademark of Omega Research, Inc.) only Dial Data and Telescan offer the option of providing end-of-day data in the proprietary Omega format.

Data Reliability

Real-Time Data

For the futures trader with an intraday emphasis, it is always unnerving to encounter a bad tick. A program such as TradeStation has the necessary tool to correct such an error fairly quickly. Fortunately, a bad tick often stands out like a sore thumb on a real-time chart as shown in Figure A. 1.

Another problem relates to the speed of data delivery. At some point, many traders, particularly those with an intraday orientation, will find that data timeliness becomes of paramount importance. There are two methods of determining the data speeds of each vendor. The first compares two different data feeds side by side. This is, in most cases, not possible. The second involves comparing ones current data feed with that of another vendor via a telephone call. The vendor on the phone can then announce each tick on a particular security and the trader may then compare this stream of data with that appearing on his or her computer screen. A variation on this is to get two vendors on different phone lines at the same time and then see whose ticks are more timely.

Also, some data providers end their trading day at midnight, instead of at the end of the floor session, as the exchanges do. The result is that the open, high, and low prices may be off substantially. This may prove critical to traders who rely on such information in their trading strategy.

In addition, certain providers do not correct their data errors after the fact. Some traders will not find this disarming, whereas others who value data accuracy for backtesting purposes will.

months of more current data stored on a hard drive. This current data can be accumulated, each day, a few hours after the market close. This downloaded data sits on the users hard drive to be seamlessly merged with the historical CD data to produce price charts at the snap of a mouse button.

Some data vendors also offer bimonthly or quarterly CD updates which, on installation, automatically remove the last two or three months worth of redundant data from ones hard drive. This automatic removal feature may be unwanted if it deletes data you had carefully cleaned of any bad values and replaces it with data that has not been as well scrubbed. Further details on data accuracy are described in the next section.

With respect to end-of-day data, the two means of product differentiation lie in price and file format. The general price range for daily downloading of an unlimited number of quotes runs between $20 and $50 per month.

Almost all vendors produce data files in ASCII format. Some produce data in Metastocks proprietary file format. For the user of Omega Researchs SuperCharts®, (SuperCharts® is a registered trademark of Omega Research, Inc.) only Dial Data and Telescan offer the option of providing end-of-day data in the proprietary Omega format.

DATA RELIABILITY

Real-Time Data

For the futures trader with an intraday emphasis, it is always unnerving to encounter a bad tick. A program such as TradeStation has the necessary tool to correct such an error fairly quickly. Fortunately, a bad tick often stands out like a sore thumb on a real-time chart as shown in Figure A. 1.

Another problem relates to the speed of data delivery. At some point, many traders, particularly those with an intraday orientation, will find that data timeliness becomes of paramount importance. There are two methods of determining the data speeds of each vendor. The first compares two different data feeds side by side. This is, in most cases, not possible. The second involves comparing ones current data feed with that of another vendor via a telephone call. The vendor on the phone can then announce each tick on a particular security and the trader may then compare this stream of data with that appearing on his or her computer screen. A variation on this is to get two vendors on different phone lines at the same time and then see whose ticks are more timely.

Also, some data providers end their trading day at midnight, instead of at the end of the floor session, as the exchanges do. The result is that the open, high, and low prices may be off substantially. This may prove critical to traders who rely on such information in their trading strategy.

In addition, certain providers do not correct their data errors after the fact. Some traders will not find this disarming, whereas others who value data accuracy for backtesting purposes will.

months of more current data stored on a hard drive. This current data can be accumulated, each day, a few hours after the market close. This downloaded data sits on the users hard drive to be seamlessly merged with the historical CD data to produce price charts at the snap of a mouse button.

Some data vendors also offer bimonthly or quarterly CD updates which, on installation, automatically remove the last two or three months worth of redundant data from ones hard drive. This automatic removal feature may be unwanted if it deletes data you had carefully cleaned of any bad values and replaces it with data that has not been as well scrubbed. Further details on data accuracy are described in the next section.

With respect to end-of-day data, the two means of product differentiation lie in price and file format. The general price range for daily downloading of an unlimited number of quotes runs between $20 and $50 per month.

Almost all vendors produce data files in ASCII format. Some produce data in Metastocks proprietary file format. For the user of Omega Researchs SuperCharts®, (SuperCharts® is a registered trademark of Omega Research, Inc.) only Dial Data and Telescan offer the option of providing end-of-day data in the proprietary Omega format.

Data Reliability

Real-Time Data

For the futures trader with an intraday emphasis, it is always unnerving to encounter a bad tick. A program such as TradeStation has the necessary tool to correct such an error fairly quickly. Fortunately, a bad tick often stands out like a sore thumb on a real-time chart as shown in Figure A. 1.

Another problem relates to the speed of data delivery. At some point, many traders, particularly those with an intraday orientation, will find that data timeliness becomes of paramount importance. There are two methods of determining the data speeds of each vendor. The first compares two different data feeds side by side. This is, in most cases, not possible. The second involves comparing ones current data feed with that of another vendor via a telephone call. The vendor on the phone can then announce each tick on a particular security and the trader may then compare this stream of data with that appearing on his or her computer screen. A variation on this is to get two vendors on different phone lines at the same time and then see whose ticks are more timely.

Also, some data providers end their trading day at midnight, instead of at the end of the floor session, as the exchanges do. The result is that the open, high, and low prices may be off substantially. This may prove critical to traders who rely on such information in their trading strategy.

In addition, certain providers do not correct their data errors after the fact. Some traders will not find this disarming, whereas others who value data accuracy for backtesting purposes will.