Question

You decide to redesign your undergraduate lunch survey from the previous item to improve its sampling method. Describe two ways you could improve your sampling, mentioning the potential advantages and limitations of each.

Answer 1

Following are the two improved sampling techniques:

1. Simple Random Sampling

• Simple random sampling is the most basic form of probability sampling.
• With this method, elements are drawn from the population at random, and all elements have the same chance of being selected.
• Simple random sampling can be done with or without replacement.
• Advantages:

i) A selected sample is representative of the larger population from which it was drawn only when probability sampling method has been used.

ii) It permits researchers to precisely estimate the amount of variance present in a given data set that is due to sampling error.

• Limitations:

i) Although conceptually a very straightforward procedure, in practice, simple random sampling is relatively difficult and costly to execute.

ii) It is impossible or impractical to enumerate every element of the population of interest, which rules out simple random sampling.

2. Systematic Sampling:

• Systematic sampling is a slight variation of simple random sampling that is more convenient to execute.
• To start the sampling process, a random number between one and 10 is chosen, and the element on the list that corresponds to this number is included in the sample.
• This randomly selected number is then used as the starting point for choosing all other elements. Say, for example, the randomly selected starting point was 7 in a systematic sample with a sampling interval of 10. The 7th element on the list would be the first to be included in the sample, followed by the 17th element, the 27th element, and so forth.
• Advantages:

i) A selected sample is representative of the larger population from which it was drawn only when probability sampling method has been used.

ii) It permits researchers to precisely estimate the amount of variance present in a given data set that is due to sampling error.

• Limitations:

  i) When the elements are arranged in some nonrandom pattern, systematic sampling will not necessarily yield samples that are representative of the populations from which they are drawn