A sample is defined by Babbie (2007) as any portion of the population less than the total.
Sapsford and Jupp (2006:26) define a sample as a “set of elements selected in some way from a
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population.” Therefore sampling refers to “selecting a part to represent the whole” (Rao, 2005:263), or cases to observe (Durrheim, 2006:133). Bryman (2004:417) observed that sampling can be done on context or participants. He added that sampling of context came before sampling of participants, especially in qualitative research. According to Durrheim (2006:50), any researcher must justify the choice of the sampling strategy they employ in their study.
There are two major sampling procedures in research: Probability and Non-Probability. In probability sampling, every unit in the population has an equal chance of being selected in the sample. Non probability sampling is used in situations where the sample is selected based on the subjectively judgement of the researcher. The present study applied both purposive and random sampling methods, because they gave the researcher the best opportunity to get the type of data that was needed for the study. The rationale for the choice of each of these sampling approaches is discussed later in this section. Student sample sizes for each university were determined using the Krejcie and Morgan (1970) sample size table for small samples (see Appendix XV). Using this table, population figures were checked against corresponding sample sizes and recorded. Krejcie and Morgan (1970) observed that no calculations are required when using this table. The resultant samples derived for this study are distributed among the various universities, as illustrated in Table 4.2. The total sample for students was 147.
The sampling frame for the students constituted a list containing names of students registered in the Psychology programme during the time of study, which was provided by the departments.
In some universities, this list was missing and the researcher used the lists of students registered to take a core fourth-year Psychology course where all final year students were expected. Using the sampling frame identified, a probability sampling technique was applied to select the sample for student respondents. This technique gave each student the same chance of being selected (Creswell, 2013:158). Mugenda (2008:188) observes that simple random sampling is convenient when the sampling frame is small and the population well-defined. Therefore the present study applied the simple random sampling method to gather data from student respondents. According to Durrheim and Painter (2006:135), other probability sampling techniques include systematic sampling, stratified sampling and cluster sampling.
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Purposive sampling was used to select the sample for psychology lecturers from each university. Purposive sampling is used when a sample is deemed by the researcher to best serve the purpose of the study (De Vos et al., 2011:232; Mugenda, 2008:196), so that units of analysis are carefully selected, based on how best they are placed in answering the research questions and providing needed information (Bryman, 2004: 418; Sheppard, 2004:94; Cohen, Manion & Morrison 2007:114). Bryman further defined purposive sampling as a non- probability sampling, where the researcher does not seek a sample of the participants randomly, but carefully chooses for their relevance to the research questions. Additionally, a non- probability sampling procedure can often be implemented more quickly than probability sampling procedure (Michael, 2011). Purposive sampling was applied to identify lecturers teaching core psychology courses at the time of the study by perusing the timetables at the offices of heads of Psychology departments in the various universities. The sampling frame for lecturers comprised a list of names of lecturers who were teaching in the psychology department at the time of the study. Four lecturers were selected from each university by ensuring that all levels of teaching from first to fourth-year were represented. The total sample for lecturers from the four universities comprised a total of 16 respondents. Once the four lecturers per university were identified, the researcher booked appointments for interviews with the assistance of the office of the head of department for each university.
The final category of respondents was made up of librarians, with the sampling frame being a list of professional librarians availed through the office of the university librarians. Purposive sampling, which is a non-probability sampling procedure, was applied to select those who formed the sample. The Librarians purposively selected included the heads of reference and reader services, instructional librarians or other librarians who directly interacted with students in meeting their information needs. The selected librarians were chosen for their knowledge of information literacy and in many cases are the ones charged with planning and teaching IL.
Among the merits of purposive sampling is the selection of the best sample possible, in the judgement of the researcher or expert, and the convenience of the method. However, purposive sampling is criticised for not being able to represent the entire population, calling on the researcher to be as objective as possible when selecting participants. Furthermore, Johnson and
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Christensen (2008:239) observe that the findings from purposive samples are not easily generalized. Four librarians were selected from each university after consultations with the university librarians’ office to ensure that those chosen had or were participating in IL training.
A total of 12 librarians were selected from all the universities, as shown in Table 4.2.
Table 4.2: Sample sizes Subjects University
A
University B
University C
University D
Total
Students 43 28 48 28 147
Librarians 3 3
3 3 12
Psychology
Lecturers 4 4
4 4 16
Total 50 35
55 35 175