That is a mixed method approach adopted. You can mitigate your biases by dealing with your positionality . It is very important to note that the paradigm for qualitative research is subjective and one needs to know why in addition to using random sampling to make a case from an objective point of view , you want to use a non probability sampling technique (snowball). is it the case that you want to achieve synergy from the limitations of both techniques or there are some inherent factors you want to achieve from some specific people which will consolidate your quantitative findings? You must have some specific purpose based on your research questions or hypothesis.

Before I can comment on this question, I would need to know more about the portions of your project that are associated with each type of sample, and more specifically, what the goal is for each type of sample.

Hello

Sampling Methods There are two main sampling methods, each of which has its own methods:

1. Probability Sampling

2. Non probability Sampling

If the goal of the researcher is to measure the variables in the sample and generalize them to the community, such as a study to determine the prevalence of dental caries in the community, this goal will not be met by non-probability sampling.

Possible sampling methods should be used.

Probability sampling includes several sampling methods:

- Simple Random Sampling

- Systematic Random Sampling

- Stratified Sampling

- Cluster Sampling

- Multistage Sampling

Snowball sampling is a non-probability sampling method when the units under study are not easily identifiable. Especially when these units are very scarce or a small part of a very large community.

When qualitative researchers go to the field for data collection, they have actually thought of and planned how and from whom they would collect data. They have even set some criteria for the selection of the participants. There are however some challenges, among which the lack of identifying the target participants (in some research) that well achieve the criteria set ahead. In this case, researchers start by visiting the main setting and making some informal interaction(s) with those (researchers think they) who achieve the criteria (and this implies a kind of random sampling in itself, and some researcher use this as a pilot study). When some of those interviewees recommend some colleagues/friends/peers etc. for you (the researcher) to interview on the basis of the interaction(s) with them on your topic and so on, then it is that you are using snowball technique. I still however think that if you still come across some participants in a random way, you can interview them (and simply explain why and how such interviews are serving your study)!

Hope this helps!

All the best!

Abdulghani Muthanna, your use of the word "random" does not match its meaning in quantitative research, where it defines a sample where everyone has a known probability of being included in the sample (e.g., an equal probability of inclusion in a simple random sample). Instead, the way you are using "random" comes closer to meaning unplanned.

David L Morgan, thank you for your comment. My earlier comment concerns qualitative inquiries wherein researchers go to the field and communicate with several persons (sometimes randomly) so as to find the participants suitable for the criteria they set ahead. The process might continue especially when the data is not saturated! Thanks again!

By the way, reading chapter 12 (sampling, pp. 202-227) of the edited book (8th edition) by Louis Cohen, Lawrence Manion, and Keith Morrison (2018) could be valuable!