James,

You might reconsider using either 'mean' or 'median' as a value to predict what to use as a sales value. As someone already pointed out, you have 'outliers' from time to time ($200,000+), and you may want to put these into a separate category. The other problem, is that you appear to have a trend of increasing values, so that the mean/median of previous years will underestimate next year's value. Maybe because of inflation, or just increasing prices. There may be other statistical procedures that will give you better estimates.

....just food for thought,
Pete

>Greg,
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>It happens frequently that we will sell one foal for $200,000 plus and the next one for $10,000.
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>At what point do you categorize a single sale price as shewed and therefore a "special cause" or "out of control". Is there a formula to help determine this?
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>It looks like we need to do all the available comparisons and then try to decide which ones apply to the goal we want to achieve.
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>We kind of get a "feel" whether a mare is a successful producer, and if there's a number that we can come up with that closely coincides with that "feeling" then maybe it can be used to help make the decision quicker.
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>Jim
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>>You should probably also take a look at the variance and standard deviation of those numbers as well. The variance is the standard deviation squared. The smaller the variance, the less the values vary from the average. The standard deviation measures the degree to which the values differ from the average of all the values. The smaller the standard deviation, the less the values vary from the average.
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>>In your original example the number 10 price, $250,000, really skews the average. Statistically it would be considered an "special cause" or "out of control" point. If you take it out the average of the 9 remaining numbers more closely approximates the median, if I'm remembering the example correctly.
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