Sampling

A definition of sampling is:

“the process of selecting units (e.g., people, organisations) from a population of interest so that by studying the sample we may fairly generalise our results back to the population from which they were chosen.”

59 Sampling decisions are often influenced by research paradigm, objectives and available resources, including time, budget, constraint, access (Wilmot, 2005). Sampling approaches were often divided between probability and non-probability types. Probability sampling is often used in quantitative studies to obtain a sample that statically represent the target population in order to draw statically validated inferences. In contrast, qualitative research does not normally use statistics to validate an inference or conclusion. Indeed, one occurrence of a phenomenon in the sample was valid for analysis (Rithcie et al., 2003). Non-probability sampling is normally used in qualitative research (Wilmot, 2005).

This study used a purposive sampling, which is a type of non-probability

sampling. A purposive sampling targets any subjects that meet specific inclusion criteria. When there are different groups targeted in the sample, the group size can be balanced during the sampling process (Black, 1999). In a purposive sampling, the participants are not chosen at random and the sampling criteria are more important than the sampling size (Wilmot, 2005).

The objective of this study was to investigate hospital practice related to patient discharge process and the completion of a discharge summary record. This objective was achieved through an instrumental case study based on the practice in the case study NHS Hospital Trust. Thus, the target population are hospital doctors who work in the case study NHS Hospital Trust. Furthermore, the participants were asked to undertake the simulation of completing a discharge summary record. Thus, the sampling criteria required the participants to have at least one year experience of completing discharge summaries in actual practice. Additionally, only potential participants from medicine, surgery, physiotherapy and paediatrics specialities were approached in order to match with the patient case notes that had been prepared.

60 Quantitative research often defines the sampling size based on statistical

validation requirements, and a sample size of 30 is often the minimum number for statistical testing. In contrast, qualitative research often uses a small sample for several reasons. Firstly, the qualitative research is labour intensive, and analysing a large sample of qualitative data is often an unattainable objective (Wilmot, 2005). Secondly, qualitative research focuses on constructing meaning from data, not on a generalised hypothesis. Every deviation from general patterns in the data is of importance for inductive analysis in qualitative research, rather than the frequency of the occurrence (Crouch and McKenzie, 2006). However, there is a saturation point, where additional sampling will not generate any more or new information and values (Rithcie et al., 2003). The concept of saturation was proposed to decide the sample size in qualitative research (Glaser and Strauss, 1967; Mason, 2010).

Consequently, defining sampling size before the study commenced could be argued to be a premature decision. However, the NHS Research Ethics Committee require the estimated sampling size, along with the total time spent with

participants, to be specified in the research proposal. This information is

particularly important to judge how much resource the research will expend on the case study organisation, and twelve participants were initially targeted. During this study, 18 potential participants were approached and ten responded. After eight interview transcripts were analysed, no substantive new findings emerged from the data. Thus, the ten individuals that made up the sample in this study were deemed sufficient.

The low response rate (56%) was due to the route originally chosen to recruit participants. Initially, potential participants were identified through Directors of Medical and Surgical Departments in the case study NHS Hospital Trust. Email communication was used to contact the potential participants and provide an invitation letter (see Appendix 3) and information sheet (see Appendix 4). If they responded to the email and agreed to participate, an interview appointment was

61 made, and a simulation package containing patient case notes, an instruction sheet and RCP discharge summary proforma were handed to them prior the interview. If there was no response, a follow up email was sent to them twice at two weekly intervals. However, this strategy proved to be unfruitful and the response rate was low. Approximately ten potential participants were identified in this way yet only two participants responded. Moreover, it took a long time for them to respond, two to three months after the first contact. From the two participants who responded, it was evident that participants were unlikely to read the simulation package before the interview.

Four months into the data collection and having made little progress, an alternative strategy was employed. Once potential participants were identified, they were contacted directly by telephone or approached face to face. The information regarding the study was explained. In the face to face contacts, they were invited to read the information sheet themselves and if they agreed to

participate, an interview appointment was made directly. The participants received the simulation package when attending the interview session. This strategy

reduced the complexity and the length of the recruitment procedure.

In addition, a snowball approach (Black, 1999) was used in the recruitment process, where two of the respondents were asked about other potential

participants. With this approach, potential participants who met the sample criteria and were willing to participate could be identified. This approach turned out to be productive and generated a high response level. Eight potential participants were approached in this way, and seven agreed to participate. The simulation and interviews were undertaken within two weeks of the first contact with the participants.

On reflection, the recruitment experience was instructive in revealing that a simple procedure and direct contact is more effective for recruiting “busy” hospital doctors, and also booking the interview appointment directly on first contact

62 reduces the risk of delays and cancellations. The hospital doctors were helpful when approached appropriately. However, complex and lengthy procedures, prolonged email communication and a passive approach were not productive.

When the participants attended the simulation and interview session, they were invited to read a consent form and ask questions if they wished to. The simulation and interview were undertaken if they agreed and signed the consent form. They then chose one patient case that suited their speciality and were asked to complete a discharge summary using the RCP discharge proforma. After the simulation, the participant was interviewed.