Question

What is double sampling (two-phase sampling)?

a) Sampling from two different populations simultaneously
b) Two samples collected at different times
c) Sampling twice from the same population
d) Using two different sampling techniques in succession

Answer 1

Double sampling is defined as sampling twice from the same population. It is not about sampling from different populations, at different times, or using multiple techniques. Specific examples given show how different sampling methods can yield diverse results, though both represent the same population accurately.

Step-by-step explanation:

Double sampling, or two-phase sampling, refers to sampling twice from the same population. This technique is not defined by sampling from two different populations simultaneously, nor by two samples collected at different times, nor by using two different sampling techniques in succession. In the scenario where Doreen and Jung sample different groups of students using systematic and cluster sampling respectively, we see an example of how different sampling methods yield different samples. Even if both used the same method, their samples could differ due to the randomness inherent in sampling. Neither sample would necessarily be incorrect, simply different representations of the same population.

For the additional questions from 1.2 Data, Sampling, and Variation in Data and Sampling:

1. The number of times per week is quantitative discrete data.
2. The sampling method used in the exercise provided is systematic sampling.
3. The duration (amount of time) is quantitative continuous data.
4. The colors of the houses are qualitative (categorical) data.

The population in the exercise would be the residents around the park in San Antonio, Texas.