Comparing to a t distribution with 13 degrees of freedom, the P -value is 0.112.
Conclusion:
Because the P -value = 0.112 > α = 0.05, we fail to reject the null hypothesis. We do not have convincing
evidence that there is a difference in the number of days of wear between the new formula and the old
formula.
Solutions to Practice Test 1, Section II, Part B
- a. The experimental units are the plots of land. The treatments are the three types of spreaders. The
response variable is the amount of fertilizer dispensed.
b. There seems to be a slight difference in the amounts dispensed, but with the large amount of
overlap between the groups it is not very convincing evidence of a difference.
c. There seems to be a strong association between the operator and the amount dispensed. Jackson
and Sara dispensed smaller amounts with all three spreaders than the other operators. Bill and
Miya dispensed larger amounts.
d. Miya’s mean amount dispensed is
e.