
128 Empirical Research in Software Engineering
Step 1: RQ from problem statement
RQ: Is there a difference in coupling values for faulty classes and coupling values for
nonfaulty classes?
Step 2: Deriving hypothesis from RQ
In the rst step, the hypothesis is derived from the RQ:
H
0
: There is no statistical difference between the coupling for faulty classes and
coupling for nonfaulty classes.
H
a
: The coupling for faulty classes is more than the coupling for nonfaulty classes.
Mathematically,
H
H
0
:
:
µµ
µµ
CBOCBO
CBOCBO
faulty nonfaulty
afaultynonfau
()
=
>
lltyfault
onfaulty
or CBOCBO
()()
<µµ
Step 3: Determining the appropriate test to apply
As the problem ...