Question

Which of the following sampling method is referred as double sampling?

• A. Multistage sampling
• B. Stratified sampling
• C. List sampling
• D. Multiphase sampling

Hint:

Double sampling is a specific, two-stage case of multiphase sampling. Think of the "phases" as steps in collecting increasingly detailed levels of data from a subset of samples.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Forest inventories and statistical surveys utilize different sampling techniques to estimate tree volume, biomass, and population parameters efficiently and cost-effectively.

Step 2: Detailed Explanation:
Let us define the sampling terms to find the synonym for double sampling:
- Double Sampling Multiphase Sampling: In this sampling technique, a large, relatively inexpensive first-phase sample is taken to estimate an auxiliary variable (for example, canopy cover from aerial photographs).
Subsequently, a smaller, highly detailed second-phase sub-sample of the first-phase units is selected to measure the primary variable of interest directly on the ground (for example, timber volume).
This two-phase approach utilizes the correlation between the auxiliary and primary variables to improve estimation accuracy at a lower cost, and is technically termed Multiphase sampling.
Let us review the incorrect options:
- Multistage sampling: Involves dividing the population into primary sampling units, from which sub-units are selected, and then final units are sampled within those sub-units.
- Stratified sampling: Divides a heterogeneous population into homogeneous subpopulations (strata) and samples independently within each stratum.
- List sampling: Uses a predefined list of sampling units as the selection frame.
Therefore, double sampling is equivalent to multiphase sampling.

Step 3: Final Answer:
The sampling method referred to as double sampling is Multiphase sampling.