Simple Random Sampling

Examples of Simple Random Sampling in the following topics:

• Sampling Techniques

  • In a simple random sample (SRS) of a given size, all such subsets of the frame are given an equal probability.
  • However, SRS can be vulnerable to sampling error because the randomness of the selection may result in a sample that doesn't reflect the makeup of the population.
  • As long as the starting point is randomized, systematic sampling is a type of probability sampling.
  • Cluster sampling generally increases the variability of sample estimates above that of simple random sampling, depending on how the clusters differ between themselves, as compared with the within-cluster variation.
  • In quota sampling the selection of the sample is non-random.

• Types of Polls

  • An opinion poll is a survey of public opinion from a particular sample.
  • This poll is generally a short and simple survey of likely voters.
  • In the deliberative opinion poll, a statistically representative sample of a community is gathered to discuss an issue in conditions that further deliberation.
  • Citizens are invited by modern random sampling techniques to participate; a large enough sampling group will provide a relatively accurate representation of public opinion.

• Analyzing Data

  • It expresses the amount of random sampling error in a survey's results.
  • The confidence level, the sample design for a survey, and in particular its sample size, determines the magnitude of the margin of error.
  • If the exact confidence intervals are used the margin of error takes into account both sampling error and non-sampling error.
  • If an approximate confidence interval is used then the margin of error may only take random sampling error into account.
  • Polls typically involve taking a sample from a certain population.

• Conducting Polls

  • Contact sampled individuals and collect data from those who are difficult to reach
  • Survey samples can be broadly divided into two types: probability samples and non-probability samples.
  • Stratified sampling is a method of probability sampling such that sub-populations within an overall population are identified and included in the sample.
  • If the response option is yes/no then you will only know how many, or what percent, of your sample answered yes/no.
  • Also, the wording should be kept simple: no technical or specialized vocabulary.

• Constructing Public Opinion Surveys

  • An opinion poll is a survey of public opinion from a particular sample, and is designed to represent the opinions of a population.
  • An opinion poll, sometimes simply referred to as a "poll," is a survey of public opinion from a particular sample .
  • Useful in describing the characteristics of a large population assuming the sampling is valid.
  • For example, polls or surveys that are conducted by calling a random sample of publicly available telephone numbers will not include the responses of people with unlisted telephone numbers, cell phone numbers, who are unable to answer the phone, and who do not answer calls from unknown/unfamiliar telephone numbers.
  • Advance letter: A short letter sent in advance to inform the sampled respondents about the upcoming survey.

• Defining Public Opinion

  • Public opinion can be accurately obtained through a random sample survey, if done correctly.