I need to divide a large numberical table into 5 breaks....Help!

[Bryan]

I have a large crop production yield database table. I would like to create a
query/report that would break the yield into 5 natual breaks. I have figured
out how to use the switch function to manually type in different class
breaks, but it is a trial and error process. I would like to find a way for
access to automatically update those ranges as more data is added.

Any ideas?

Thanks-Bryan

 

[Bryan]

Yes, I will try to explain a little better. I have a large database of
production data for corn and soybean fields in Iowa. The database is made up
of yield, soil types, soil fertility, types of corn and soybeans planted,
etc. I have a linked table with my GIS software, so this data is actually
spatial data. Each farm field is divided into 60 ft square cells, and then
each cell is populated with it's related attributes. So each farm field could
have 2000 records.

My final linked table is a table that has numberous fields combined. It has
150,000 records. Each one of those records has the same attributes. So each
one of those 150,000 has a yield number, a soil phosphorus number, etc. What
I want to do is get a natual break of the yield, and then find the average
phosphorus for that range. I would like 5 ranges.

When I manually create ranges, such as below:

Yield:
0-120
120-160
160-180
180-200
200>

I often get too many records in one break. I would like access to define the
breaks for me, by dividing the data into 5 equal ranges instead of me having
to constantly adjust those ranges to match the data.

Does this help?

THanks!

 

[Jerry Dennison \(MVP\)]

Since your ranges do not define equal bin sizes, I must assume that the
quantities within the ranges defined are approximately equal. If this is so,
what purpose could it serve statistically? If you made a histogram of the
data and the bars are all the same height you do not know what your
population distribution really is. As a rule, bin sizes are the same so that
your frequency distribution gives you a graphical picture of your population
distribution. What exactly are you trying to do?

Jerry Dennison
MS Access MVP

 

[John Vinson]

I have a large crop production yield database table. I would like to create a
query/report that would break the yield into 5 natual breaks. I have figured
out how to use the switch function to manually type in different class
breaks, but it is a trial and error process. I would like to find a way for
access to automatically update those ranges as more data is added.

Any ideas?

Thanks-Bryan

I'm with Joseph. I'm sure some query expression could be derived, but
not knowing what constitutes a "natural" break nor how you are using
Switch() at present, I'm at a loss to make any useful suggestion.

More info please!

John W. Vinson[MVP]