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One of the key elements in back-testing and/or optimization of trading strategies is the back-test (history) data. Fortunately MetaTrader 4 enables the user to download the back-test data through a special dialogue box called History Center Window. To see the dialogue box from Tools menu select History Center or alternatively press F2 (see image).

(click image to enlarge)

The list on the left side of the dialog box shows available symbols (usually currency pairs). Depending on your broker you may see them categorized under special groups. If you select a time frame under a symbol you see the values assigned to each bar on the right side of the window. For example the image shows the values for 1 Minute chart of GBP/USD. Each row shows the date and time, open price, high, low, close, and volume for each bar. The icon to the left shows whether the bar is bullish (close greater than open - white), bearish (close less than open - blue), or doji (close equal to open - cross). You usually need to double-click the symbol to see the time frames and then you need to double-click the time frame to see its list.

The History Center window also enables you to take the following actions.

• Download back-test data: Click the download button to download back-test data. MetaTrader downloads the data from MetaQuotes servers. You usually see a warning message about the source of data. Click here to watch a video about downloading back-test data. Click here to know how to build all your time frames data correctly.
• Add Bar: If you believe a bar is missing from the list then you may click Add and then use the Bar dialog box to add the new bar (see the following image).
  
  
• Edit Bar: Select a row (bar) from the list and then click Edit to change the values assigned to the selected bar. This option helps you to correct mistakes. This button uses a dialog box similar to the one used by the Add button.
• Delete Bars: Select a row or multiple rows (with the help of Ctrl or Shift keys) and then click Delete to remove them from history. This action creates holes in the history so make sure you really want to do this.
• Export data: Click Export to save the history in a file. The default file type is CSV (comma delimited files). You may however choose other file types such as PRN (text files for printing) or HTML (Hypertext Markup Language documents).
• Import data: If you already have back-test data (for example downloaded from a website) then you may import it into MetaTrader by clicking the Import button. The acceptable files are HST (MetaTrader History Files) or different text files such as CSV, PRN, or TXT. Make sure the file is compatible with MetaTrader data structure prior to importing.

History Center plays an important role in the process of developing, testing, and optimization of trading strategies. Since the data source is not usually the same as the actual data offered by your broker and also since there are holes and irregularities in the data this system is not perfect. Nonetheless, this is probably the best source to help you test your strategies right now. Remember that no matter what you do, the past performance of a system does not guarantee its future behaviour. In other words, never fall in love with your back-test results.

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