Which data do I use to create a OHCL chart on Excel?

[mattatthestudio]

For arguments sake, let's say the period is one minute. Should I use the Back prices for 'High' and Lay prices for 'Low' and pick from those values for Open and Close. This is probably a really stupid question but I only discovered how these charts work yesterday evening...and I'd had a wine... Any other advice on creating these charts would be helpful. Eventually I want to add standard deviation bars to this too. Finally using my A level Stats..

[doris_day]

Thats an interesting issue.

I think in the financial markets its usually the mid-point between the Bid and Ask prices. But that's because the spread is generally constant, or at least fairly tight. With Betfair markets the B/A spread can become very large. Prices are also more volatile, particularly in many of the more illiquid markets.

My own view would be to stick with one of the prices and personally I'd keep to the Back price.

[milfor]

I wouldn't use the back or lay price for that. If the best price is taken there is sometimes a very big gap behind it (sometimes even to 1.01 or 1000 respectively). This would lead to a ridiculous and misleading movement in the chart. I would use the last price matched instead. A movement there has more significance than a movement of the back or lay price that sometimes only means: For some seconds there were no competitive offers in the market.

[doris_day]

Yes, I think you're right milfor. Well spotted.