You hear about correlations and see these on reports, such as Field Top Ten and Grower Top Ten, but may be confused as to what they really mean. After reading this, you should have a better understanding!
Correlation is:
- a measure of the strength of relationship between two variables
- a practical way to gauge the way variables interact
- Correlation tells us what factors increased (or decreased) as yields increased (or decreased).
Correlation IS NOT:
- a ‘magic bullet’ or ‘Easy Button’
- proof that X caused Y with 100% certainty (You having children and you developing grey hair may be correlation, but you having children probably is not the cause of your grey hair.)
BIGGER Number = STRONGER Relationship
In our Agricultural world, the really big numbers are not realistic.
- This is OK. There are hundreds of factors affecting yield in agriculture.
- So if we have a .5 or -.5 correlation, that’s a pretty good relationship
Direct Correlation Example: Yield increases as soil test phosphorus parts per million increases.
Inverse Correlation Example: Yield increases as soybean population decreases.
