Sample size

According to Bryman, the sample size should neither be too small to achieve data saturation or theoretical saturation nor too large to conduct a deep analysis.237

This research includes two types of ENGOs, which were approached in each country according to the criteria. Based on this, in the UK, two ENGOs were considered as respondents for each type at the outset: Greenpeace UK and Friends of the Earth UK (FoE) were interviewed as respondents who had become involved in GE, while TearFund and Practical Action were selected as participants who have not engaged with GE. TearFund was chosen because, although it is not an ENGO, it is a group with climate interests.238

After analysing the data and generating basic categories, more samples were approached in order to achieve a theoretical saturation. Finally, six NGOs including Greenpeace UK, FoE, World Wildlife Fund (WWF), Action Group on Erosion, Technology and Concentration (ETC

237 _{Bryman (n 47).}

238 _{I have approached other non-ENGOs which also include climate change as one of their focus areas. However,}

due to access issues, they turned down my requests for interviews. This is why TearFund is the only non-ENGO included in my research.

Group), Biofuel Watch, and Blue & Green Tomorrow were selected as respondents who have become involved in GE while three NGOs, namely TearFund, Practical Action, and ClientEarth, were invited as respondents who do not engage with GE. A brief introduction to the scope of selected groups in the UK is shown in Table 1.2 in the appendix. The reason why these six NGOs were considered as appropriate respondents is that they are the main players that actively participate in GE policy discussion and campaigns in the UK. This is based on the responses from participants as well as results from online searching. In terms of the three non-involved groups, they were selected because, although these groups have not engaged in GE, their focus lies in climate change, which includes the area of GE. It is meaningful to explore why they are not involved in GE since they do focus on a broader area of climate change. In China, due to the fact that none of ENGOs have been involved in GE, all respondents were selected within the type of non-involved groups. In detail, CBCGDF, HDIEO, TBEAS, IPE, Lvxing Taihang and Greenpeace China were chosen as participants for interview. These groups were interviewed because, in order to avoid selection bias when sampling, they cover a wide range of types of ENGOs concerning climate change in China, namely: government-supported NGOs, business-supported NGOs, large grassroots NGOs, small grassroots NGOs, and international NGOs. A brief introduction to these Chinese groups is provided in Table 1.1 in the appendix.

In terms of sample size, this research involves a relatively small number of NGOs as respondents. One may argue that the small number could produce problems in generating reliable findings. However, a small number of in-depth qualitative interviews, although it

may still have disadvantages, can be justified in the literature. According to Wilmot, the small number of cases is a feature of qualitative sampling, as ‘a phenomenon only need appear once to be of value’.239

It contrasts with quantitative sampling in that it does not emphasise statistical significance.240

From a practical perspective, including a large quantity of in-depth interviews may go way beyond one’s ability to deal with data. In terms of how many qualitative interviews is enough, almost every scholar in methodology gives the same answer ‘it depends’.241

A consensus has been made that this includes research objectives, validity and practical concerns like time and resources.242

These factors, which have impacts on determining the number of interviews, can be summarised as inside and outside factors. Inside factors refer to methodological and epistemological considerations while outside factors include time and resources.243

Although it is inside factors that should determine the number of interviews in theory, normally it is outside factors that play a predominant role, especially for early career researchers.244

A concept of saturation is often employed to justify the number of interviews. It refers to a point ‘of diminishing return[s] to a qualitative sample because as the study goes on more data does not necessarily lead to more information’.245

However, achieving a stage of saturation is challenging as ‘it forces the research to combine sampling, data collection, and analysis’.246

In addition, saturation is an ideal condition for data collection while in practice, it is 239 _{Amanda Wilmot, Desiging Sampling Strategies for Qualitative Social Research: With Particular Reference to the} Office for National Statistics' Qualitative Respondent Register (Survey Methodology Bulletin-Office For National Statistics, 2005). 240 _Ibid. 241 _{Sarah Baker and Rosalind Edwards, How Many Qualitative Interviews Is Enough? Expert Voices and Early Career} Reflections on Sampling and Cases in Qualitative Research (National Centre for Research Methods Review Paper, 2012). 242 _Ibid. 243 _{Uwe Flick, Designing Qualitative Research Book 1 of The SAGE Qualitative Research Kit (London: Sage} Publications 2008). 244 _Ibid. 245 _{Mark Mason, ‘Sample Size and Saturation in PhD Studies Using Qualitative Interviews’ (2010) 11 Qualitative} Social Research Art. 8. 246 _{Bryman (n 47).}

difficult to achieve this stage or researchers often claim to achieve it but are unable to prove it.247

This is because the idea of saturation offers little practical guidance.248

In terms of my research, it achieves saturation to some extent as no more new valid information was identified after data collection. The respondents were basically holding similar views on the explanations for their involvement or non-involvement. What’s more, the special situation concerning GE in the UK and China also plays a vital role in determining the number of samples. In relation to the involved UK NGOs, although I cannot approach all involved groups due to constraints on time, at least all the main players regarding GE discussion in the UK were covered. With regard to non-involved ones, which is an even a larger quantity, although it is not feasible to include all of them due to limited time and resources, at least well-known groups involved in climate change were selected in order to explore why they do not engage with GE. This made the selection manageable and non-random from a potentially huge sample group. In the context of China, due to the fact that no NGOs have engaged with GE, the samples were only selected under the categorisation of non-involved groups. With limited time and resource, although it is unpractical to interview every well-known environmental group in China, a good variety of well-known environmental groups, with different types and sizes, were included which can avoid selection bias to some extent.