89
highlighted using this technique is the inability to check if the informants’ reflections
were true of their actual behavior (Welker, 2010)
.
In studies on dictionary use, tests may be used to verify the effects of
dictionary look-ups on any kind of L2 linguistic activities like reading, writing,
vocabulary learning, etc
.
In a test, subjects perform a given task and the results of
which are then examined and evaluated (Welker, 2010)
.
Experimental studies, on the other hand, seem to be very common in
dictionary use research
.
However, Tono (2001, pp
.
71-72) distinguished between
various
experimental designs, based on Cohen & Manion (1994)
:
Pre-experimental design
:
In this type of design, a group of subjects are given a test to measure some
variable (e
.
g
.
the number of spelling mistakes in an essay); after
a new factor has been
introduced (e
.
g
.
instruction on dictionary use), the subjects are given another test to
see if that factor influenced the subjects’
performance
.
Quasi-experimental design
:
The investigation in this design is conducted with two groups of subjects who
are not randomly selected; for example, two classes of students could be chosen
.
In
both groups, two tests are given
.
In the “experimental group”, a new factor is
introduced between the tests (e
.
g
.
using the dictionary), but not in the “control group”
.
As such, the researcher verifies if
that factor has any influence
.
90
True-experimental design
:
The only difference between this type and the quasi-experimental design is
that the two groups have been randomly selected
.
Tono (p
.
71) argued that “In theory,
random assignment … controls all possible independent variables
.
In practice, of
course, it is only when enough subjects are included in the experiment that the
principle of randomisation has a chance to operate as a powerful control”
.
Tono
(2001, p
.
71) classified the studies carried out by Summers (1988), Hulstijn (1993),
Hulstijn, Hollander & Greidanus (1996) and Knight (1994) as
true experiments
.
Yet, one major problem for tests and experiments is the objectivity of
evaluation and interpretation of the results
.
Therefore, it is recommended that the
evaluation of results is carried out by more than one person (for example, in the case
of scoring an essay or a translation task), unless there is little margin for biased
interpretations, as in the case of multiple-choice tests (Welker, 2010)
.
Among the aforementioned wide range of methods, experiments and log files
were chosen as the main investigative techniques for this study
.
Taking into account
their validity, reliability, appropriateness for the research objectives, and feasibility,
the two methods were combined to reveal a more complete picture of how CDs use
could influence L2 learners’ performance
.
I adopted a quasi-experimental design since the study was carried out with two
groups of subjects who were not randomly selected
.
I could by no means have
91
students from different classes participate in the study because it was impossible to
gather those randomly selected subjects to attend several treatment sessions
considering that they had different classes and perhaps would find it disruptive
missing a class each now and then
.
In addition, I could not guarantee that the
randomly selected subjects would be willing to attend all the treatment sessions,
especially if we know that the phases of the study were carried out near the end of the
academic year in summer, when it usually gets very hot and most of the students
would rather stay at home to revise for their final exams
.
Any irregular attendance or
withdrawal would have affected the process
of obtaining data negatively
.
4
.
3
.
Instruments and Data Collection Methods
4
.
3
.
1
.
Reading Tests from the TOEFL PBT
This study employed two authentic reading tests (Appendix A and B) adapted
from a TOEFL PBT Reading Collection, which contains the previously administered
paper-based TOEFL tests
.
The Reading Comprehension Section requires reading
passages on various topics and answering questions about them
.
The questions
typically ask about information that is stated in or implied by the passage, as well as
knowledge of
some of the specific words
.
The passages’ themes were very similar to the ones the students usually have
in “Culture of the Language”, which is a very important subject in
their major, dealing
with issues in American or British history and civilization
.
The first passage dealt