Standard AIM = buy (sell) as and when AIM indicates.
Ocroft method is where all sequential AIM indicated trades aren't actually traded but mentally accumulated and then when the next AIM review indicates no AIM trades being apparent then actually place the market order for all of the mentally accumulated trades
So if in January AIM indicates buy $1000 of stock, and then again in February AIM says buy another £1200 of stock, but then in March no AIM trade is indicated then you buy £2200 of stock in March (having 'ignored' trading of the January and February trades).
The idea is that you don't chase down runs, but accumulate all of the buys you would have made and deploy a single larger trade after a bottom reversal.
There are two ways as I see it to record Ocroft trades. Either you maintain a paper AIM and just buy/sell the accumulated trades as above, leaving the paper AIM running as normal (that records each and every trade being placed as soon as indicated). Or you adjust the PC, #Shares etc according to the Ocroft based trades (single larger trades), which induces a different set of #shares held compared to the standard (model) AIM.
Of the two it looks to me as though the former is the more productive. i.e. run a paper AIM as a model and use that model to identify how much to trade and when - and not let the accumulated trades value have any input into the #shares setting of the model AIM.
What I'm broadly seeing with the Ocroft approach is that when single AIM trades occur then often you'll buy at a higher price by delaying the purchase until the following month (assuming no AIM trade is indicated the next month), so it typically relatively loses out for such cases - but typically not by that much. When however there is a sizeable down run and AIM indicates repeated buy trades month after month, then having accumulated all of those trades and deployed after AIM stops buying you not only preserved cash reserves for longer, but 'averaged in' at a much lower 'average' price. A much more significant 'saving' (difference).
Some say AIM has a "Lichello Flaw" where after a buy another buy can be immediately indicated. Lichello was aware of that and described it as being a feature - not deploying too much too soon so-to-speak. Others suggest AIM sells to the greedy, buys from the scared. With Ocroft's approach its more a case of buying from those that have capitulated - but where such capitulation has bottomed and the share price started to reverse back up again. Some call that bottom-fishing - looking to lump a sizeable amount in after the share price looks to have dived deeply, bottomed and started to rise back up again.
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