Data Priority: Local or Data Service Provider?

[aventeren]

Howdy--

Let's say that I have downloaded a bunch of tick data from BMT, but some of the data was corrupt or off.

Let's say that I also am connected to a data service provider that is providing me with 120 days of tick data (or more, it doesn't matter).

Let's say that I am then backtesting a period of time where the BMT data was corrupt but the data service provider's data was obviously good.

When running a backtest, is my local or data service provider's data used in the backtest?

What are best practices for insuring sound local data?

What questions am I not asking pertaining local data versus data service provider data?

Thanks,

Aventeren

[NinjaTrader_Brandon]

Hello Aventeren,

Thanks for your post.

If you do a backtest over a time period in which you do not have all the data new data for the entire period will be download from your connectivity provider should you be connected to them. If no new data is needed for the back test then no data will be downloaded and it will access it as is from your system.
You can ensure you have correct data from your provider by downloading the data under Tools Historical Data> download

[aventeren]

So if I have data on my local machine and I sign up for a data provider (i.e., IQFeed), my local data will be in a first position if it's there and the data provider's data would be in a second position?

Is there a way to have the data feed be in a first position and my local data in a second position?

I have downloaded a bunch of tick data from BMT, and after doing some in-depth analysis on the data, I have come to the conclusion that I would like to try out a data provider's data--at least for backtesting. Therefore, I'm interested in seeing whether I'll have to delete all of this old tick data from my database file or something else.

Thanks,

Aventeren

[NinjaTrader_Kyle]

Hello,

This would require that existing data be deleted. Data can be deleted through the Edit tab of the Historical Data Manager window. (Tools > Historical Data Manager) Please see the following link to our Help Guide for more information: http://www.ninjatrader.com/support/h...t7/editing.htm

[aventeren]

3 minute response time. Man I love NT Support.

That's what I thought on the data deletion.

Thanks,

Aventeren