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Null hypothesis: Ho:
There is no real difference between
the two insect traps in
terms of their ability to capture insects. Any
observed difference is therefore due to chance
(random error)". Ho: xu
=
x15
Data: Trap UV
n=10, =
74 insects s=
16
Trap 15W
n=10, =
42 insects
s= 18
Analysis:
| xu
- x15
|
32
t
=
----------------
=
-----------
=
4.202
﴾Sxu
- x15﴿ 7.616
calculated t = 4.202
critical t(0.001, 18df) = 3.92
t(calc)
exceed the t(crit) for 0.001 Therefore reject Ho.
Summary: There was a difference observed between the two traps
in terms of the mean number of insects captured in 24 hrs. The UV trap
A showed mean of 74 and the 15w lamp showed a mean of 42 insects captured.
This difference was highly significant statistically, and is unlikely (less
than 0.1% likely) to have occurred by chance alone. We can reject the null hypothesis as stated above, and
conclude that on the basis of the data provided, that the UV device was much
more effective than the 15w lamp.
(xu
-
x15):
32
18 df t: 4.202 ,
P < 0.001
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