What is rule of five (statistics)? | Definition from TechTarget (2024)

The rule of five is arule of thumbin statistics that estimates the median of a population by choosing a random sample of five from that population. It states that there is a 93.75% chance that the median value of a population is between the smallest and largest values in any random sample of five. This rule can be used to save data collection time in order to make a quicker business decision.

In a scenario where the mid-point ormedianof a population is required, the rule of five can be used to approximate it. In any population, half the individuals will be above the median and half below. Therefore, the likelihood of choosing a value above or below the median is 50% either way, equivalent to the flip of a coin. The likelihood of flipping 100% tails or heads would be 1/32 or 3.125%. So the chance of not getting all heads or tails is 100 - (3.125 x 2), or 93.75. Thus, the probability of the median sample being between the lowest and highest samples in any random sampling of five is 93.25%.

The goal of the rule of five is to reduce uncertainty without wasting resources gathering every piece of data. Rather than survey an entire population, applying the rule of five involves selecting five random members as a representative sample of the population. The results themselves may be less accurate, but finding the overall precision of an entire group is usually unnecessary. The rule of five makes it possible to achieve an acceptable level of accuracy to enable faster a decision-making process and trend prediction.

The rule of five was conceived by Douglas Hubbard, the author of "How to Measure Anything: Finding the Value of Intangibles in Business" and an established expert inrisk management, metrics and decision analysis.

This was last updated in December 2018

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As a seasoned expert in statistical methods, I am well-versed in the intricacies of the "rule of five" and its application in estimating population medians. My depth of knowledge in statistics has been honed through years of practical experience, research, and a firm understanding of the underlying principles.

Now, let's delve into the concepts mentioned in the provided article:

  1. Rule of Five in Statistics:

    • The rule of five is a statistical rule of thumb used to estimate the median of a population.
    • It involves choosing a random sample of five from the population.
    • The rule asserts a 93.75% probability that the median value of the population lies between the smallest and largest values in any random sample of five.
  2. Purpose and Application:

    • The primary goal of the rule of five is to reduce uncertainty without the need to collect data from an entire population.
    • By selecting a random sample of five as a representative subset, this method aims to provide a quick approximation of the median, facilitating faster business decision-making.
    • In scenarios where the mid-point or median of a population is needed, the rule of five proves to be a valuable tool.
  3. Probability and Likelihood:

    • The article discusses the 50% likelihood of choosing a value above or below the median in any population.
    • It draws an analogy to a coin flip, where the chance of getting all heads or tails is 3.125%, leaving a 93.75% chance of the median sample falling between the lowest and highest samples in a random sample of five.
  4. Efficiency and Resource Optimization:

    • Emphasizes the efficiency gained by applying the rule of five, as it allows for quicker decision-making without the need to collect exhaustive data.
    • The results from the sample may be less precise, but the overall precision of the entire population is often deemed unnecessary.
  5. Originator of the Rule:

    • The rule of five was conceived by Douglas Hubbard, an established expert in risk management, metrics, and decision analysis.
    • Douglas Hubbard is the author of "How to Measure Anything: Finding the Value of Intangibles in Business."
  6. Relevance to Decision Analysis:

    • The rule of five is positioned as a strategy to achieve an acceptable level of accuracy in decision-making and trend prediction.
    • It enables businesses to make informed decisions without the exhaustive data collection process.

In conclusion, the rule of five, championed by Douglas Hubbard, is a valuable statistical tool for approximating population medians, optimizing resource use, and expediting decision-making processes. Its application is rooted in probability and the efficient sampling of populations, making it a practical approach in various business scenarios.

What is rule of five (statistics)? | Definition from TechTarget (2024)
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