3.4. Study population and sampling framework.
The study population will consist of all Freda Rebecca Gold Mine employees working at the mine.
Proctor (2003), highlights that sampling is adopted in research as in most cases when the populations of interest are too large to work with, thereby presenting cost, time and resources constraints. Therefore, sampling makes the research manageable, and cost effective, while enhancing the accuracy of findings by accelerating the speed of primary data collection and processing (Brown, 2006). The stratified random sampling technique used falls under probability sampling which according to Babbie (2007) affords every member of the population an equal chance of being selected into the study sample. This creates a highly representative sample with numerous advantages that include absence of systematic and sampling bias as well as augmented reliability of the findings.
A multistage sampling technique will be used to select a sample of 123 respondents from a total population of 1022. Firstly, the population from all departments at the mine will be identified and purposively using a stratified random sampling method only 80 employees from Mining, Safety, Health and Environment (11), and 7 from Human Resources departments will be selected as key informants and for convenience purposes. Sub-areas will be listed and a simple random sampling used to select only one section from the mining department including the Human Resources and Safety, Health and Environment. Finally visits will be made to all the selected areas and a complete list of the ones with exposure and including those who enforce were compiled. The list prepared in each selected area will serve as a sampling frame and individuals will be randomly selected after a simple individual listing.
3.5.2. Inclusion criteria
All FRGM permanent employees, casual employees with a 6 month and above contract or have been with FRGM for more than 6 months and are still at work.
3.5.3. Exclusion criteria
All employees with lower back pain as result of an accident, a deformity, or previous spinal injury, pathological backache due to infection, backache due to malignancy and congenital problems. Temporary, seasonal or casual employees as well as senior management are excluded from the study.
3.5.4. Sample Size and Distribution.
Researcher adopted the equation developed by Cochrane (1963) for large populations to yield a representative sample for proportions.
Where n_0 is the sample size, Z^2 is the abscissa of the normal curve that cuts off an area ? at the tails (1 – ? equals the desired confidence level, e.g., 95%), e is the desired level of precision 5%, p is the estimated proportion of an attribute that is present in the population, and q is 1-p. The value for Z is found in statistical tables which contain the area under the normal curve.
Finding the values of p and q where total population is 1022 and 98 employees from identified stratums.
FRGM population is small, thus the researcher will reduce the sample size slightly because a given sample size provides proportionately more information for a small population than for a large population. Therefore, the sample size (n_0) will be adjusted using the formula for finite population correction for proportions, which is
Where n is the sample size and N is the population size.
3.6 Data collection techniques
Primary data collection will be done using questionnaires, surveys, direct observation and in-depth interviews with selected participants. Secondary data collection will involve a review of the FRGM documents and other reports as well as a search of any relevant publications. Quantitative data will be gathered using closed ended questionnaires during survey, while for qualitative data mixture of open-ended and closed questionnaires, observation and in-depth interviews will be employed. The use of different techniques is meant to capitalise on the strength of the techniques and improve on the validity of the findings. A self-administered questionnaire and a semi structured interview will be used for data collection which together with an information leaflet about the study will be distributed to workers at their workplaces.
Secondary data will be collected from the mine clinic records where employees diagnosed with LBP are recorded in the clinic register, National Social Security Authority (NSSA) claim forms