Non-probability sampling method is used in this study. Non-probability sampling is a sampling technique where the probability of any objects being chosen for a sample cannot be determined. A main pros of non-probability sampling is that it saves time and money compared to probability sampling. It is easier to use and can be employed when the sample population is relatively small, as is the case of this study. Additionally, non-probability sampling uses non-random selection – it depends on the subjective view of the researcher, while probability sampling does not.
More specifically, this study employs quota sample (a type of non-probability sampling method), which is often used in market research, where the groups (i.e. males and females) in the sample are corresponding to the groups in the population. That is, the relevant factors such as gender, age, and family size are controlled to ensure the proportion. This type of non-probability sampling is useful when relevant control characteristics, such as gender, age range, and household size, are identified to ensure the sample presents population regarding the factors of interest1.
Following the criteria (quota and inclusion criteria), a set of 35 questions were sent to selected subjects who satisfy all requirements. The quota criteria are comprised of 3 factors: gender, family size, and city. At least 50% of the sample was women, 30% was single households, and nearly 80% of sample who grew up in developing cities in Vietnam.