I suppose, first and foremost, that the total physical number of the organisations to be studied should be ascertained. If the total number is 30 and above which is statistically large, a sample can be drawn using appropriate sample size determination formula and sampling technique. Thereafter, the respondents expected to complete the research instrument can be obtained from the Human Resource Departments of each of the organisations depending on the unit of analysis adopted which can macro-level (senior staff and above), groups or individuals (micro-level). The number of respondents from each organisation is then summed up to arrive eventually at the population of the study.Again, if the population of respondents is large too, sampling can be carried out also as mentioned earlier on. Bowley's formula can be used to determine the copies of the research instrument to be administered to each organisation to ensure that proportionality is achieved.Your perspectives are awaited because, meaningful scientific life, demands that we learn, unlearn and relearn. Cheers.