Question

Q1. Explain why cluster sampling is a probability sampling design. Describe a situation where you would consider the use of cluster sampling.

Q2. Nonprobability sampling designs ought to be preferred to probability-sampling designs in some cases. Explain with an example.

Answer 1

ANSWER 1:Cluster sampling is a probability sampling design because firstly population is divided into N groups and those groups are called clusters.and then researcher randomly selects n clusters to include in the sample from N clusters by using random probability.

As we know that cluster sampling methods are of two types . Type 1 is One-stage sampling in which all of the elements within selected clusters are included in the sample and type 2 is Two-stage sampling in which a subset of elements within selected clusters is randomly selected for inclusion in the sample.

Example: Suppose we want to interview the customers who visits SUBWAY. In this case it may not be possible to list all of the customers of a chain of SUBWAY. However, it would be possible to randomly select a subset of SUBWAY (stage 1 of cluster sampling) and then interview a random sample of customers who visit those SUBWAY (stage 2 of cluster sampling).

ANSWER 2: Non probability sampling designs ought to be preferred to probability-sampling designs in some cases where we want to have the desire result.

Example: Suppose we want to show that certain school is doing good. For this purpose we will select only those students from school who have good grades in exams. Here we selected students with non probability. In this case each student does not have equal chances of being included in the sample.