With DDE you must hard-code any input in the formula's syntax, you cannot reference a cell. Meaning if I wish to pull an item into my spreadsheet, the input must be fixed. For example, if I want to quote the last traded price of AAPL, the function must reference that ticker specifically. Now, let's say I want to change that quote to GOOG, my function will not change to reference the new input. Thus, the need to pull in large volumes of data. With RTD you can reference cells, and change them at will. Now, there are workarounds such as VBA codes, concatenating cells, third party software, etc., but why bother. Also, DDE's performance will suffer once you start pulling large amounts of data.
regarding a good data feed. DTN IQ pipes data into spreads. I have not used it for options data, but I am fairly certain it would work. Here is the link https://www.iqfeed.net/ninjatrader/index.cfm?displayaction=start&promo=1717496
what is your insight on trading back spreads? what are some things i should consider regarding: implied vol relative the hist vol; strike spreads, above, around, below the current price action; and time to expiry.
just out of curiosity.. why are you interested in trading backspreads? not to put you on the spot but i'm just wondering what about them has you interested in them.. your risk changes over time and ranges in price.. i'm interested in what your trying to accomplish or express and how this strategy relates.. heres an old thread.. found this googling searching for "ratio spreads" http://www.elitetrader.com/vb/printthread.php?threadid=74786
thank you for the link, very much appreciate that. this option strategy appears to provide risk adjusted returns if directional movement occurs and also seems to provide a slight hedge if the move goes otherwise coupled with financing the position. It seems to appear that the risk is that volatility in price action relative expiry is less than expected. Therefore, am seeking some experience on building these positions relative the greeks, strikes, expiry, and price action using fundamental and technical analysis.
to add to my answer. to implement tactical trading in an effort to operate in markets that are directional with volatility for speculative purposes. to max risk adjusted return making the most of available capital. my experience has been to use single strategy in directional markets as the short position to generate premia appears to be more of a drag on performance if the directional result works.