Farmer Jones wants to make an informed decision on which variety of corn to use. She recognizes that not only variety of corn, but also other variations in soil composition, fertility and drainage, will determine the yield. She decides to run an experiment to compare two corn varieties, A and B. She has a field with 36 plots available for the experiment. On 18 plots she will plant variety A and on the other 18 plots she will plant variety B. She wishes to determine whether the two varieties produce significantly different yields/
But how should she decide which plot receives which variety of corn?
Her husband suggests one option of plot assignment. Put all the
A variety on one side and put all the B variety on the other side. So the
field will look like:
| B | B | B | A | A | A |
| B | B | B | A | A | A |
| B | B | B | A | A | A |
| B | B | B | A | A | A |
| B | B | B | A | A | A |
| B | B | B | A | A | A |
Her mother suggests another option of plot assignment. Use a checkerboard
technique of assignment. So the field will look like:
| A | B | A | B | A | B |
| B | A | B | A | B | A |
| A | B | A | B | A | B |
| B | A | B | A | B | A |
| A | B | A | B | A | B |
| B | A | B | A | B | A |
Your teacher will give you the "Truth", the
actual yields for each variety in each plot. Please remember that
the Truth is not known to the farmer and
is never known to the experimenter - that is why he or she is doing the
experiment!!!! For each of the plot assignments calculate the average
for variety A and for variety B. Which appears to be the better variety?
Do the two
methods contradict each other? ___________________________________________________
The farmer is confused. She doesn't know what to do!!!!!! Fortunately
the farmer next door has a day job as an AP Statistics teacher. He
suggests that randomizing the selection process might help.
How would you set up the randomization process, using either your calculator
or a random
number table? _________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
Carry out the process and assign the plots here:
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