|
Grand Rapids, MI | OK, I do know a fair amount about Math (Bachleors degree with Math/Econ major, 3 stats classes) I can hear the collective groan of pain from the crowd...lol
So I think I understand what you want to accomplish. You want to use your sample strip(s), which you have reason to believe are not representative of the entire field, to estimate the yield of the entire field, had it been harvested for grain. Your idea is to take the historical information you have about the field to adjust the yeld in the sample strip(s) to make a better estimate that represents the entire field. Is this correct?
Now I do not think I fully understand the method you are undertaking. It sounds like you are taking all the observations for a given year when the entire field was harvested for grain, then dividing each of them by the average of all of them, then multiplying each by a constant (207)? If this is the case, your average of the results should be 207. This will not tell you anything.
Here is what I would suggest. There are probably better ways to set this up, but given what we have to work with now, you should be able to come pretty close with this method. Also it is pretty intuitive, so it should sell well to your customer. If you have the ability, do a query of past years yield files to get the average yield in that year of the area where you harvested each of the strips this year. Then take that average and divide by the average of the entire field for each strip. Next, for each strip, average these numbers for all the years. Then take this number and multiply by this years yield for the corresponding strip. Finally average the result for the three strips. This should give you a pretty good estimate of what the entire field would have yielded.
To explain this, we are basically figuring how well each strip typically yeilds compared to the field. Then we are applying this same proportion to this year. Then finally averaging all 3 sample strips.
So thats how I would do it. With these directions you should be able to do it yourself if you have good GIS software. It sounds like you do from what you are already doing. Or if you are uncertain, or don't have the time or right software, send me the yield files and I can do it. Should be between $100 and $200.
As for your qestion about the mean medium and the average, let me give some definitions. I think you may have meant to say the median. The median is simply the number that falls in the middle of the list if you listed all the numbers in order. I would not use it in this case. The mean is what most people think of as the average. It is figured simply by adding all the observations and dividing by the total number of observations.
Hopefully this is what you were looking for, if you have more questions, let me know. | |
|
using my yield map for silage compensation
