Triangulation is qualitative cross-validation. It assesses the sufficiency of the data according to the convergence of multiple data sources or multiple data collection procedures (Wiliam Wiersma, 1986). Triangulation in credibility test is interpreted as checking data from various sources in various ways, and at various times. Thus there are source triangulation, triangulation of data collection techniques and triangulation of time.
The explanations of Triangulations above are:
1. Source Triangulation
Triangulation of source to test the credibility of data is done by checking the data that has been obtained through several sources. For example, to test the credibility of the data about a person's leadership style, the collection and testing of the data obtained is done to a subordinate who led, to a supervisor who assigns, and to a co-worker who is a co-operation group. From the three sources, it cannot be averaged as in quantitative research, but it can be described and categorized; which is the same view, which is different view, and which is specific one of the three sources. The data that is analyzed by the researchers and produces further conclusion, then the data sought an agreement with the three sources of data.
2. Technique Triangulation
Technique Triangulation to test the credibility of the data is done by checking the data to the same source with different techniques. For example, the data obtained by interview, and then checked by observation, documentation, or questionnaire. If the three techniques of data credibility testing result in different data, the researcher has to do further discussion to the relevant data source or another. Or all may be right because different perspective.
3. Time Triangulation
Time also often affects the credibility of the data. Data that are collected by interview in the morning when the speaker is still fresh does not have many problems, so it will provide more valid and more credible data. In order to test the credibility of the data, it can be done checking by interview, observation, or other techniques in different time or situation. If the test results produce different data, it is done repeatedly until finding the certainty of data.
Triangulation can also be done by checking the results of the study, from other researchers who are given the task of collecting the data.
