5.3 Population and sample
5.3.1 Sample
consuming, especially if it is very large or distributed over a large geographical area;
and
· Cut costs: Observing, interviewing, or using
questionnaires to collect data from every element of a population could be very costly if the population is large and/or geographically distributed over a large area.
Bickman and Rog (1998:13) note that, sampling is very important in data collection as it allows a researcher to study a subset of the units of interest and then to generalize to all units with a specifiable degree of error.
Babbie (1998:198) points out that the primary considerations in sampling are size and representativity. The size must be adequate so that estimates about the characteristics of the phenomena are made with reasonable precision. Grinnell and Williams (1990:127) recommend that a 10% sample is sufficient for controlling sampling errors. Both size and representatives contribute towards the achievement of the sampling objectives which, according to Smit (1995:16-17), are as follows:
· To make certain deductions and generalizations about the population;
and
· To accept or reject statistical hypotheses about a population.
A sample of 20% (eight EPWP-defined projects out of 40) and 100% EPWP management and operational staff were considered adequate for this study. It is also important to note that the sample was representative of all population groups in order to avoid bias.
As noted in chapter 2, the Department of Public Works in KZN comprises one Head Office and four Regions (eThekwini Region, Southern Region, Midlands Region and North Coast Region), where District offices are situated and where the programme is being implemented. The management of the EPWP follows the same sequence;
Provincial Management is situated at the Head Office and Regional Management is situated in the regions.
The sample for this study comprised the EPWP Provincial Coordinator, four Head Office EPWP Management Team members (the General Manager: Operations;
Senior Manager: EPWP; Manager: EPWP; and Assistant Manager: EPWP), Regional Managers and Assistant Managers from each of the four regions and 11 District Managers (one per District). Bickman and Rog (1998:XVII) stress the importance of triangulation in qualitative research design; hence, a sample was also drawn from four Head Office Operational Teams (Development Workers or Officers) eight Regional Operational Team members (two Development Workers or Officers from each region), 80 beneficiaries of EPWP-defined projects focusing on construction (2 projects X 4 regions = 8 projects X 10 beneficiaries = 80) and eight foremen (one from each project).
The sample for this study therefore consisted of a total of 124 participants.
5.3.1.1 Sampling strategy
Both probability sampling and non-probability sampling were used in this study.
a) Probability sampling
Jupp (2006:238) defines probability sampling as any method of sampling that uses some form of random selection. Every member of the population has an equal probability of being selected (Van Der Waldt, Van Niekerk, Doyle and Du Toit, 2002:291-292).
b) Stratified random sampling
Simple random sampling was the most suitable method for this study as it involves dividing the population into homogeneous groups, each containing subjects with similar characteristics (Cohen and Manion, 1994:87). This method of sampling is designed to ensure that the sample has certain characteristics that are representative of the population on key variables. The population is divided into different groups (called strata) so that each element
of the population belongs to one and only one stratum (Bryman and Cramer, 2001:98). After the population has been classified into strata or subgroups, a random sample is taken from each subgroup. Stratified sampling offers the possibility of greater accuracy by ensuring that the groups which are created are represented in the same proportion as in the population (Bryman and Cramer, 2001:99). In this study the population of the EPWP-defined projects in KZN was divided into four groups, according to the regions, and thereafter, random sampling was done per region indicated below:
· Southern Region,
· North Coast Region,
· Midlands Region ; and
· EThekwini Region.
Two projects were randomly selected in each region (2 projects X 4 regions = 8 projects). All regions were requested to identify two EPWP-defined projects, compile a profile and agree on a date for the visit. From the eight identified projects, simple random sampling (a table of random numbers) was undertaken to select 10 EPWP beneficiaries per project (8 projects X 10 beneficiaries = 80 beneficiaries). The stratified random sample was a useful blend of randomization and categorization, thereby enabling both quantitative and qualitative research to be undertaken (Cohen and Manion, 2000:101). Each EPWP-defined project is allocated a foreman who plays a supervisory role. Thus, eight foremen (one per project) participated in the study. This resulted in a total of 88 participants who were beneficiaries.
c) Non-probability sampling
According to Van der Waldt et al. (2002:292) non-probability sampling is not random as members do not have an equal opportunity of being selected; some have no chance at all since the selection of members is based on a researcher’s judgment of the characteristics of the population and the needs of the study.
Purposive or judgmental sampling was the most suitable method to select key informants from the EPWP management. Welman and Kruger (2001:189) note
that, on account of their position or experience, key informants have more information than regular group members and are better able to articulate such information. For the purposes of this study, EPWP Management and officials of the department who are directly involved in the implementation and management of the EPWP were selected as key informants. The focus group for purposive sampling therefore included Senior Management, Middle Management, Junior Management and those involved in implementing the EPWP. This made up a total of 36 participants.
5.3.1.2. Access to the sample
According to Cohen et al. (2000:98) researchers need to ensure not only that access is permitted, but is, in fact, practicable. A researcher needs to establish the best means of accessing the respondents, thus enabling a high completion and return rate. For the purposes of this study, the questionnaires for the EPWP Management and Operational Staff (DSD officials) were distributed to and collected from the Head Office.
All eight EPWP projects were visited on the scheduled dates (each region being allocated two dates) and questionnaires were distributed, administered and collected on the same day to ensure full completion and a comprehensive understanding of the contents.
Permission to conduct the research was received from the Head of Department in the KZN Department of Public Works (Refer to Annexure F).