Meanwhile, the quantitative data the students’ speaking scores were analyzed by calculating the mean scores of the pre-test and the post-test. The
mean scores of each test were compared. The increase of the mean scores indicated that the students’ speaking skills were improved.
F. Validity and Reliability of the Data
To obtain the research validity, the researcher applied the criteria of validity proposed by Anderson et al. in Burns 1999:161-162. There were five
types of validity. They were democratic validity, outcome validity, process validity, catalytic validity, and dialogic validity.
1. Democratic validity
It is related to the extent in which the research is truly conducted collaboratively and allows for the inclusion of multiple voices. It means that in the
process of action research, the researcher collaborated with all parties which become the members of the research such as the teacher and the students, to
discuss about the process of implementation of group work. To gain the democratic validity the researcher conducted the interviews with the research
members. This aimed to know their comments or opinions about the research. 2.
Outcome validity This validity is related to the notions of actions leading to outcomes that
are „successful’ within the research context. This was obtained from the reflections in every meeting
and the students’ scores of speaking pre-test and post- test.
3. Process validity
It is related to the „dependability’ and „competency’ of the research. It means that the worth of the research took on the process not merely on the results
of the research. So, the process was done systematically in order to get the complete information to describe the process in implementing group work. The
researcher did an observation during the implementation by using observation sheets and interviews after the implementation.
4. Catalytic validity
It is related to the extent to which the research allows participants to deepen their understanding of the social realities of the context and how they can
make changes within it. This was done by making the reflections of students’ attitudes toward the actions and also interviewing the participants.
5. Dialogic validity
This validity parallels the process of peer review which are commonly used in academic research. It means that in conducting the action research when
the researcher wants to take a decision, the researcher consulted others or other members of the research, the expert or even to the researcher herself in order to
consider the action or to get a conclusion. To gain this validity, the researcher conducted some discussion with the English teacher.
To obtain the trustworthiness, the researcher used a triangulation technique Burns, 1999: 163-164. Burns 1999: 164 proposed four types of triangulation.
They are time triangulation, space triangulation, investigator triangulation and theoretical triangulation. However, in this research the researcher only used three
