Sample selection

In a quantitative research approach, the researcher aims to select a sample that can represent the whole population through a mathematical or systematic process because of the high cost and time it will require to recruit the whole population (Maltby et al., 2015). The result of this research can sometimes be generalised to the whole population. However, in qualitative research the researcher collects data from a small sample of individuals within the population to gain an in depth knowledge on the perception or views or behaviour of these individuals on the topic of interest.

However, the appropriate sample size in this approach is one that adequately answers the research questions (Marshall, 1996). The sample size can be determined by the methodological approach of the research, as grounded theory research would need to report data saturation before stopping data collection; and the nature of the research question (Braun & Clarke, 2013). Data saturation is the point whereby information gathered from new participants does not produce any new information, where the participants continue to repeat the information that other participants have mentioned earlier during data collection (Corbin & Strauss, 2015).

For instance in studies that aim to answer simple questions or less detailed studies the number of participants might be below ten, meanwhile for complex questions a large sample size might be appropriate (Marshall, 1996). However, because this study aims

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focus groups discussions and five interviews was assumed to be appropriate to understand the topic. Also, cost and time constraints were factors that were

considered when deciding on the number of interviews and focus group discussions to conduct (Silverman, 2013). In the case of a qualitative research approach, the result cannot be generalised on the whole population but it captures a phenomenon or an essence at a particular point in time (Maltby et al., 2015). However, the result might be transferable to a group of people with similar characteristics as the individuals

recruited for the study.

In contrast to a quantitative research approach that utilises random sampling

technique to recruit participants into their study in order to generalise findings to the population, this sampling technique is not effective in understanding complex issues

regarding human’s behaviour for several reasons (Holloway & Galvin, 2017). Firstly, because of the sample size of participants recruited in qualitative research studies, if a representative sample is desirable the sampling error would be so much that bias would be inevitable in the research (Maltby et al., 2015). Therefore, the larger the sample size, the lower the sampling error; that is, there is high possibility that the researcher has not recruited the individuals within the population that would make the findings generalizable.

Secondly, due to the flexible nature of qualitative research the characteristics of the participants to be recruited into the study might not be known at the beginning of the research (Corbin & Strauss, 2015). However, the random sampling technique requires that the characteristic of the population to be studied is known at the beginning, as this is used to develop a sampling frame for the research (Maltby et al., 2015).

81 Thirdly, in qualitative research it is believed that people’s observation, understanding,

and interpretation of their own or others people’s behaviour is different; that is, it is believed that a participant’s view on a topic might be richer than another (Creswell, 2007). Therefore, picking participants randomly to answer a research question is similar to an analogy of a researcher that aims to know the reasons why electrical systems break down and then decides to randomly select participants from a

community to share their views instead of asking an electrical engineer who might give richer information concerning the topic.

This study recruited women from social and religious gatherings within Lagos state, as that was how similar studies have recruited their study participants and they had an acceptable amount of participants in their studies (Al Dasoqi et al., 2013; Baron-Epel et al., 2004; Lor et al., 2013). In addition, to ensure a holistic capturing of themes and address the inherent cultural factors within Nigerian hospital (Akinola et al., 2011), mammography practitioners were recruited for face-to-face interviews from the onset of the study. A purposive sampling method was used to recruit the participants. It is a common sampling selection method used in qualitative research studies (Braun & Clarke, 2013). According to Sandelowski (2000), it is an appropriate method that fits within the descriptive qualitative methodology, this is important as all the qualitative methodological approaches as a framework to what to use to guide the study. For example, as mentioned earlier the theoretical sampling is a sampling method that is specifically used in the grounded theory research approach.

4.3.2.1. Purposive sampling

Sampling is the process of selecting individuals from a population to acquire

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is informed by the research questions and theoretical considerations (Holloway & Wheeler, 2013). The researcher aims to recruit participants that can best answer their research questions, therefore, all qualitative sampling are purposive in nature (Patton, 2002). In convenience sampling even though the participants are close to the

researcher they would still have to be able to inform the research question before they are selected to participate in the study. However, there are arguments that this might not always be the case in some qualitative research approaches such as grounded theory, as the characteristics of the participants that would be recruited in the study might not be known at the beginning of the study because of the nature of this approach (Coyne, 1997; Finlay & Ballinger, 2006; Holloway & Wheeler, 2013). In grounded theory research, as the study progresses new theories are developed which would lead the researcher to move sampling in whatever direction the new theories lead (Sbaraini et al., 2011). However, it can be argued that as these theories are developed in grounded theory research, it leads to the researcher asking more questions and then recruiting participants to answer these questions that developed during the course of the research. Therefore, research questions might always be a determinate for the sampling in qualitative research; thus, indicating that all sampling in a qualitative research approach are purposive.

Purposive sampling is the process of selecting participants from a population for the purpose of informing the research question (Silverman, 2013). Therefore, if the study

purpose is to describe the factors affecting women’s participation in mammography

screening programme, as a result the study participants would need to have similar characteristics with the women eligible for screening programme. These characteristics are, women between the age of 40-70 years, asymptomatic women, and women

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without history of cancer. The inclusion and exclusion criteria are illustrated in table 4.1. and 4.2. below.

Table 4. 1. The focus group participants’ inclusion criteria with reasons Inclusion criteria Reasons

Women between the age of 40-70 years

This is the age group of women invited to participate in the Lagos state screening programme (Lagos State Government Ministry of Health, 2017)

Asymptomatic women This also is one of the conditions for participating in mammography screening in the Lagos state programme (Lagos State Government Ministry of Health, 2017).

Women with or without previous mammography experience

This group of women would be invited because this study aims to describe the factors affecting women that had participated and those that had not participated in

mammography screening as this will provide evidence on how to improve the mammography screening for these women. Research evidence has shown that women that are not satisfied with their mammography experience might not adhere to regular screening (Drossaert et al., 2002).

Women with or without history of breast

augmentation

Miglioretti et al. (2004) and Handel et al. (1992) give evidence that breast augmentation is not associated with increased risk of breast cancer but it decreases the accuracy of

mammography screening in detecting early breast cancer. Therefore, women with breast augmentation could be classed as low risk women.

Women living in Lagos state, Nigeria.

Women outside Lagos state might not be able to give an appropriate account of their views on factors affecting participation in the Lagos state mammography screening programme, because mammography screening outside Lagos state would require that the women pay for the service.

Table 4. 2 The focus group participants’ exclusion criteria with reasons Exclusion criteria Reasons

Women with family history of breast cancer

They are also known as high breast cancer risk women and they have high possibility of developing breast cancer

(American Cancer Society, 2014). Therefore, the age at which they begin mammography screening and frequency of screening is different from the average risk women (Lagos State Government Ministry of Health, 2017). However, their experience of breast cancer might influence their

participation in regular mammography screening.

Women with history of cancer

This group of women are also classed as high-risk women because of the possibility of cancer recurrence. As a result of this, they are advised to go for mammography examination more frequently than the average risk women.

84 4.3.2.2. Snowballing technique

The snowballing sampling technique is a type of purposive sampling technique, where the researcher recruits a participant based on their eligibility to participate in the study, and the participant then recommends other prospective participants that fit with the inclusion and exclusion criteria of the study (Braun & Clarke, 2013). The limitation of this is that people with high social connection are more likely to be recruited than the people that hardly socialise within a population (Holloway & Wheeler, 2013). A research study conducted with women within Lagos Nigeria shows that these women with lower social economic status are three times less likely to have a mammogram compared to women with higher status. It will be more useful to attempt to capture these women’s views concerning the mammography screening

programme. Therefore, the researcher conducted all of the data collection in areas in Lagos state where there were people with both low and high socioeconomic status. However, due to the limitation of the snowballing technique, women with low socioeconomic status with high social connections within these communities were more likely to have been recruited in the study.