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Better late than never, I hope. The prices have been updated for 2005, but that's not all. That's not most of it, really. But neither is it the long-fabled "new backtester" I've been promising for ages. It's something in between - most of the features of the new tester without the bits that were causing most of the problems.

An overview of what you'll get:

New prices.
It's been ages since I've been regularly updating backtester returns, but I haven't stopped collecting prices. I've just been collecting them in a different format, and now I'm using that format. So I'll be back to regularly updating the backtester every month. The new data is ID-less, where each stock is referred to only by its ticker symbol, with changes logged so I'll have the right price at the right date and symbol changes flow smoothly.

More screens.
You can now select from all the standard VL-based MI screens. By "standard" I mean what's found in the weekly rankings and/or RadiScreen. I may be missing a few, but they can be easily added - I've given up on the two-letter screen codes which makes them much easier to add. With the exception of the IBD-based screens I keep around only for historical interest, all screen picks are generated on the fly from the VL data. It won't always quite match the published rankings since I pre-exclude Toronto Exchange stocks (mostly due to missing historical prices).

Instead of just now showing the picks for anything coming from the Screen Builder, I now randomize the tickers. This lets you have an idea of how many stocks are picked and how often they're traded. You can also choose more than ten picks from the predefined screens with similarly masked tickers.

Better Performance.
The Screen Builder reads straight from the text files from VL, but only once - then it stores all fields in a binary file. I also cache a lot more than I used to. The old tester cached entire screen runs, so if you ran the same screen twice, it would pull the old one from the cache instead of re-running it. Now the Screen Builder caches at each step, so if you make a change to a screen, it only needs to run the changed part of things. I don't know if you'll notice much improved performance right off, since everyone has to rush to test things for next year (which it isn't quite yet), and might just want to see what's new anyway. I'm keeping to the same "instant" paradigm of the backtester instead of the queued model, hoping that as the cache matures things will indeed be notably quicker.

Different data.
Since Value Line stopped publishing VLIS2 data and went only with VLIS3, sometime in mid-2004, I've been reformatting the VLIS3 data "by hand". The new backtester understands the latest format, so I figured I'd extend the VLIS3 stuff back to January 2002 when it began. This has made some of the screen choose some different picks in the 2002-04 range. The are the same as they were 1986-2001 and 2004-present, though I've still noticed a few changed screen picks, some from the Toronto exclusion and some from my cleanup of price data.

New URLs.
Before you panic, let me assure that existing URL codes will still work. But anything you run will produce different URL codes. Better in my opinion, but I suppose that goes without saying. Things are shifted around a little, with the global options coming before the two-letter tester code, and subscreens separated by parentheses instead of terminated by the capital U. That second change is the good part - no more hassle to figure out how manu U's to add to you screen code to make it work, since the doubled capital letter in the screen builder are no longer a concern. It also makes the codes a little more readable.

The original set of predefined screens still have their two-letter codes for brevity, but other screens now use their canonical names (in parentheses like subscreen URL codes). I've stopped using my own variants of the common screen names, and went with the same ones the weekly rankings use. You can also put your own names into screen definitions, which will make the URL codes a bit longer but should make it easier to keep track of which screen is which.

One catch to this new URL format is it's not compatible with RadiScreen. But they don't call him The Great Radish for nothing - I'm sure there will be a new version before long (my apologies for the extra work, Radish).


I'm sure there are still bugs - aren't there always. But it seems to be working, so I'm putting it out before the new year begins. I'll be available to fix whatever breaks (I hope), and you can now dust off some of those requests that I've habitually answered with "after I get that new backtester going".

- Jamie
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