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Originally Posted by podonne
For those of you who use impact value analysis, is there a certain level that you would consider 'significant' enough to use in a system.
I understand IVs to mean that 1.0 shows that the value has no impact, i.e. the distribution if winners in the sample roughly equals the distribution of runners. So I wonder how far above or below 1.0 the impact value would have to go to show a significant effect.
Or, if anyone is reluctant to go on record with an exact figure, a method for determining it would be appreciated. I don't think the standard statistical methods are applicable.
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To expand on my previous comment, the objectives that I try to achieve in selecting and using impact values are:
(1) to the greatest extent possible, choosing factors that qualify as independent variables/significant values (if they are single-point factors); or that have independent/significant values at the top and (preferably)/or bottom of their impact-value ranges, and that have a smooth progression of impact values from top to bottom (if they are a ranking-type factor);
(2) avoiding redundancy of variables within the major handicapping categories (speed, pace, condition, class, etc), or dependent relationships among the categories, that would distort the accuracy of blending them together;
(3) if deciding between two ranking factors that measure the same handicapping element, preferring the one with the greatest range or spread from top to bottom; and
(4) when dealing with single-point factors, concentrating on significantly positive variables rather than significantly negative ones, since the positive variables have demonstrated their ability to favorably influence the horse's winning chances, regardless of what negative aspects the horse may have contained in its record.
