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1. Check trend in H1, H4 and D1 with Market Profiles

2. Signals and entry on M15 with A Tool: Peak Volume Counter

Correlation between open positions is the same as between prices of corresponding symbols.
Using of such correlations is close to arbitrage rather than to the trend following, and, of course, is more reliable way to get income.

PositionValue = PositionSize * PriceOfBaseAsset

PositionValue is value of open position in account currency.
PositionSize is size of open position in units of base asset.
PriceOfBaseAsset is current price in account currency of 1 unit of base asset.

Assuming that we completely control size of open positions, we assume that PositionSize is constant during each calculation of correlation.

I use only one assumption : we control size of open positions.
In this case size of open position is not fluctuating, randomly or in any other manner.
Consequently, value of open position is fluctuating in direct proportionality to the price of underlying asset, with constant coefficient.

I say "asset" because standard accounting in USD, for example, takes in account the cross-currency pair, for example EURJPY, as 2 positions : accounting position of asset "EUR" and accounting position of asset "JPY".

Yes, "Correlation between open positions" must sound as "Correlation between values of open positions".

Yes, I live in Russia, yes, I never crossed borders of my country, but I like to communicate, and I love English, and I study it with a pleasure.

Yes, diversification is one of the methods of risk managements based on correlation.

And in many cases, the analysis of open positions is a tool of risk management.
For example, if we are monitoring correlation between 2 opened positions, we can more precisely evaluate market risk of these positions.

Let we limit market risks of each working asset, or currency pairs, by the certain values.
Let we totaly filled all the limits.
If we see that correlation between 2 opened positions became extremely high, we must reduce size of these positions up to 2 times.

That is, for the highly correlating positions, sum of market risks must be less than limit of market risk for single position.

For this purpose does not matter wich method of calculation we use : correlation between values of open positions, or correlation between prices of underlying assets.
If we control size of positions, these methods are equivalent.

Example when we cannot instantly control size of open position : automatic trading.
If the automatic trading system computes market risks on stop-loss distance, that may depends on many factors, size of position may vary very widely from order to order.
In this case, we control limits of market risks, but not size of position, and the values of open positions depends not only on prices, but on automatic trading strategy too.
Methods of correlation calculations based on values of open positions and based on prices of underlying assets are not equivalent in such case.

And.
In MetaTrader 4 "open position" may mean "open order" or "market order", see for example : http://docs.mql4.com/trading/OrderSend

And, as I can remember, term "Correlation between open positions", or similar, is widely used in Basel II and in addendums to Basel II.

And, in the end, about single pair.
Let we trade EURJPY, and account currency is USD.
Let we found that EURUSD pair and USDJPY pair are non-correlated.
Then let we calculate that maximal allowed size of EURJPY order is equal to N lots.
And when we will find that EURUSD and USDJPY become high-correlated, then maximal allowed size of EURJPY order will equal to N / 2 lots.
That is, depending on correlation between open positions on a single pair, we can adjust market risk up to 2 times!

risk <=> deduction from capital <=> cash loss