Respondents of a recent sample survey provided names of friends they thought would be likely users of a new product. These friends were contacted, completed a survey, and asked to supply names of other likely users. Which method of sampling has been used in this survey ?
Understanding Survey Sampling Methods
The question describes a specific method used in a sample survey where initial respondents help identify and recruit subsequent respondents. Let's break down this process and identify the sampling method used.
Analysis of the Survey Process
- Initial respondents are selected for the survey.
- These respondents are asked to provide names of friends or acquaintances they believe would be likely users of a new product.
- These identified friends are then contacted and complete the survey.
- The contacted friends are also asked to supply names of other potential likely users, continuing the chain of referrals.
This method relies on the connections and referrals from existing participants to find new participants.
Identifying the Sampling Method Based on Referrals
This process, where the sample grows through referrals from initial participants, is a distinct characteristic of a particular non-probability sampling technique.
What is Snowball Sampling?
Snowball sampling is a non-probability sampling technique. It is used when potential participants are hard to find. The researcher starts with a small number of initial participants (often called "seeds"). These participants are then asked to identify and recruit other individuals who meet the study criteria from their own social network or acquaintances. The sample size "snowballs" as more referrals are made and new participants are recruited.
The survey described in the question follows this exact pattern: initial respondents provide names, and these referred individuals become the next wave of respondents, who in turn may provide more names.
Why Other Options Are Not Suitable
- Judgemental Sampling: In judgemental (or purposive) sampling, the researcher selects participants based on their own judgment and knowledge of the population. It does not involve participants referring others.
- Expert Sampling: This is a specific type of judgemental sampling where individuals considered experts in a particular field are chosen. The selection is based on expertise, not referrals from others.
- Quota Sampling: Quota sampling involves setting quotas for specific characteristics (like age, gender, location) and then finding participants who meet these quotas. While it aims for a sample with certain proportions, the selection method is typically convenience or judgemental until the quotas are filled, not through participant referrals.
Conclusion on the Sampling Method Used
The survey method described, where participants refer other potential participants based on their likelihood to be users of a new product, perfectly matches the definition and process of Snowball sampling.
Revision Table: Types of Non-Probability Sampling
| Sampling Method | Description | Key Feature |
|---|---|---|
| Convenience Sampling | Sampling participants who are readily available or easy to reach. | Ease of access. |
| Judgemental Sampling | Researcher selects participants based on their own judgment about who is typical or representative. | Researcher's expertise/judgment. |
| Quota Sampling | Sampling until specific quotas are filled for certain characteristics. | Meeting pre-set proportions. |
| Snowball Sampling | Existing participants refer future participants from their network. | Referrals from participants. |
Additional Information on Snowball Sampling
Snowball sampling is particularly useful when studying populations that are hidden, stigmatized, or hard to reach through conventional sampling frames (like lists or directories). Examples include studying drug users, homeless individuals, or members of specific underground communities. While effective for finding participants in such cases, a major limitation is that the sample may not be representative of the entire target population, as referred individuals are often socially connected and may share similar characteristics.
Important Questions from Sampling
The process of converting the analog sample into discrete form is called ______.
Which one among the following relates to the probability-based sampling technique?
In which process is the flat-top pulse amplitude modulated signal generated?
Consider a population of 3 units having values 2, 4 and 6. A simple random sample (without replacement) of 2 units is to be drawn from the population. Let M denote the sample mean of this sample. Then which of the following statements are true?
Let x(t) be a signal with Nyquist rate ω 0. Determine the Nyquist rate for y(t) = x(t)cos(ω 0t)
