Carry and momentum are diversifying, so barring any information about performance (and there isn't any statistically significant difference between them) you'd want to split your portfolio 50:50 (assuming you have the same number of trading rule variations in each camp) for optimal expected performance. An institutional fund like AHL's flagship fund has to allocate more than 50% to momentum, so has a suboptimal portfolio.
Forecasts are proportional to sharpe ratio (mean / vol), a diff of EMA is a return in delta(price) space, so the correct forecast is proportional to diff of EAM/ vol (delta(price))
GAT
Thanks for the reply. Sorry but I still don't quite understand (2). Put it in another way, say I have a signal -20 to 20 for a mean reversion asset. When the signal is at 20 means that the asset is very far from what I estimate to be fair value, hence I'm willing to bet more on the reversion. I'm not sure how this intuition works for a trend rule.
I found this old comment on your blog:
I probably missed it but do you explicitly test that forecast magnitude correlates with forecast accuracy? For example, do higher values of EMAs result in greater accuracy? I'm assuming there's an observed albeit weak correlation. I haven't yet immersed myself in your book so I may be barking up the wrong tree.
Rob Carver8 May 2016 at 17:10
I have tested that specific relationship, and yes it happens. If you think about it logically most forecasting rules "should" work that way.
Could you elaborate more on how to go about testing the relationship? The reason I ask is because if there wasn't a strong relationship, it might be more appropriate to setup the trading rule as a classifier problem: trend vs no trend.
, but interesting discussion. Reading between the lines, it seems you are saying one sensible approach is to allocate equally to carry and momentum and then apply the FDM to each style separately to alter the relative allocations? From what I recall from your posts and first book, I guess the other approach is to throw all the forecasts of all styles and variations into one optimisation (or series of optimisations when bootstrapping) and let it spit out the weights and then apply the FDM? I presume the first approach it is likely to give more stable weights?