First there was the Daily Racing Form's track variant, based on variations from track records, later modified to reflect variations from best time in a three-year time period, and averaged for different distance groups. 

Then there was the Daily Track Variant methodology of Andrew Beyer, based on class-speed pars (sometimes adjusting for or just ignoring seemingly aberrant races). 

And most recently, there are various variants conjured by computers, although their various vendors usually don't offer explanations of just how they're figured. 

Is one better than another? Should you make your own? Are they any good at all? 

Like so much of handicapping, the answers are usually vague, but not necessarily inaccurate. Yes, some are better than others, but it really depends on (1) how the original speed figures are constructed, and (2) the track you are playing. I know from experience that homemade figures are usually the very best, and well worth the effort if you are playing only one track (the amount of time needed to maintain more than one--two at most--sets of figures and variants is usually more than the average player is willing to spend). 

If you're a simulcast player who can't get to the OTB every day, there's a simple alternative that's a reasonable shortcut. You will need a set of par times, which can be obtained easily and inexpensively from commercial sources. Instead of making detailed pars, simply match the running times of each day's races with the pars, and based on what you see, use one of these designations to note the speed of the surface for the day in your notebook:

• Very Slow
• Somewhat Slow
• Neutral
• Somewhat Fast
• Very Fast

Pace-oriented players will find a useful parallel in designating a "style variant" for each day in addition to using a surface speed variant:

• Favored Early Speed Heavily
• Favored Early Speed Somewhat
• Neutral
• Favored Closers Somewhat
• Favored Closers Heavily

But the successful handicapper, the real pro, knows that the vagaries of so many factors that are interdependent cannot be represented in one Magic Number.There is and always will be a subjective element-the element that makes handicapping an art and not a science.